Expandable intravascular occlusion material removal devices and methods of use

ABSTRACT

An improved expandable removal element (16) for an atherectomy device wherein the expandable removal element (16) is movable between an expanded position and a contracted position. In one embodiment of the present invention, a single drive shaft (92) is operatively connected to the distal end of the expandable material removal element (16) for rotating the removal element (16). A catheter (178) may surround a portion of the drive shaft (92). The catheter (178) is shiftable with respect to the drive shaft (92) for moving the material removal element between the expanded position and the contracted position. In another embodiment of the present invention, dual coaxial drive shafts are employed. The inner drive shaft (312) and the outer drive (314) are shiftable with respect to one another for moving the removal element (252) between the expanded position and the contracted position. The present invention also describes several embodiments for an improved removal element (252).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S application Ser.No. 08/621,350, filed on Mar. 25, 1996, abandoned, which in turn is acontinuation-in-part of U.S. application Ser. Nos. 08/206,053, filed onMar. 3, 1994, now U.S. Pat. No. 5,501,694, and U.S. application Ser. No.08/261,813, filed Jun. 17, 1994, now U.S. Pat. No. 5,540,707, which inturn are continuation-in-part applications of U.S. application Ser. No.08/055,995, filed Apr. 29, 1993, now U.S. Pat. No. 5,490,859.

BACKGROUND OF THE INVENTION

The present invention generally relates to constructions forintravascular treatment devices useful for removing vascular occlusionmaterial from a vascular occlusion or from a vascular lumen. Theinvention more specifically relates to expandable intravascularocclusion material removal devices, as well as to methods of using thosedevices to treat vascular diseases.

Vascular diseases, such as atherosclerosis and the like, have becomequite prevalent in the modern day. These diseases may present themselvesin a number of forms. Each form of vascular disease may require adifferent method of treatment to reduce or cure the harmful effects ofthe disease. Vascular diseases, for example, may take the form ofdeposits or growths in a patient's vasculature which may restrict, inthe case of a partial occlusion, or stop, in the case of a totalocclusion, blood flow to a certain portion of the patient's body. Thiscan be particularly serious if, for example, such an occlusion occurs ina portion of the vasculature that supplies vital organs with blood orother necessary fluids.

To treat these diseases, a number of different therapies are beingdeveloped. While a number of invasive therapies are available, it isdesirable to develop non-invasive therapies as well. Non-invasivetherapies may be less risky than invasive ones, and may be more welcomedby the patient because of the possibility of decreased chances ofinfection, reduced post-operative pain, and less post-operativerehabilitation. One type of non-invasive therapy for vascular diseasesis pharmaceutical in nature. Clot-busting drugs have been employed tohelp break up blood clots which may be blocking a particular vascularlumen. Other drug therapies are also available. Further non-invasive,intravascular treatments exist that are not only pharmaceutical, butalso revascularize blood vessels or lumens by mechanical means. Twoexamples of such intravascular therapies are balloon angioplasty andatherectomy which physically revascularize a portion of a patient'svasculature.

Balloon angioplasty comprises a procedure wherein a balloon catheter isinserted intravascularly into a patient through a relatively smallpuncture, which may be located proximate the groin, and intravascularlynavigated by a treating physician to the occluded vascular site. Theballoon catheter includes a balloon or dilating member which is placedadjacent the vascular occlusion and then is inflated. Intravascularinflation of the dilating member by sufficient pressures, on the orderof 5 to 12 atmospheres or so, causes the balloon to displace theoccluding matter to revascularize the occluded lumen and thereby restoresubstantially normal blood flow through the revascularized portion ofthe vasculature. It is to be noted, however, that this procedure doesnot remove the occluding matter from the patient's vasculature, butdisplaces it.

While balloon angioplasty is quite successful in substantiallyrevascularizing many vascular lumens by reforming the occludingmaterial, other occlusions may be difficult to treat with angioplasty.Specifically, some intravascular occlusions may be composed of anirregular, loose or heavily calcified material which may extendrelatively far along a vessel or may extend adjacent a side branchingvessel, and thus are not prone or susceptible to angioplastic treatment.Even if angioplasty is successful, thereby revascularizing the vesseland substantially restoring normal blood flow therethrough, there is achance that the occlusion may recur. Recurrence of an occlusion mayrequire repeated or alternative treatments given at the sameintravascular site.

Accordingly, attempts have been made to develop other alternativemechanical methods of non-invasive, intravascular treatment in an effortto provide another way of revascularizing an occluded vessel and ofrestoring blood flow through the relevant vasculature. These alternativetreatments may have particular utility with certain vascular occlusions,or may provide added benefits to a patient when combined with balloonangioplasty and/or drug therapies.

One such alternative mechanical treatment method involves removal, notdisplacement, as is the case with balloon angioplasty, of the materialoccluding a vascular lumen. Such treatment devices, sometimes referredto as atherectomy devices, use a variety of means, such as lasers, androtating cutters or ablaters, for example, to remove the occludingmaterial. The rotating cutters may be particularly useful in removingcertain vascular occlusions. Since vascular occlusions may havedifferent compositions and morphology or shape, a given removal orcutting element may not be suitable for removal of a certain occlusion.Alternatively, if a patient has multiple occlusions in his vasculature,a given removal element may be suitable for removing only one of theocclusions. Suitability of a particular cutting element may bedetermined by, for example, its size or shape. Thus, a treatingphysician may have to use a plurality of different treatment devices toprovide the patient with complete treatment. This type of procedure canbe quite expensive because multiple pieces of equipment may need to beused (such intravascular devices are not reusable because they areinserted directly into the blood stream), and may be tedious to performbecause multiple pieces of equipment must be navigated through anoften-tortuous vascular path to the treatment site.

SUMMARY OF THE INVENTION

The present invention overcomes the disadvantages found in the prior artby providing an improved expandable removal element for an atherectomydevice. The expandable removal element is movable between an expandedposition and a contracted position and may be utilize in a single ormultiple drive shaft configuration.

In one embodiment of the present invention, a drive shaft is operativelyconnected to a distal end of the expandable material removal element forrotating the removal element. A catheter surrounds a portion of thedrive shaft. The catheter has a distal end for operatively variablycontacting the proximal end of the material removal element such thatthe removal element is rotatable with respect to the catheter. Thecatheter is shiftable with respect to the drive shaft for moving thematerial removal element between the expanded position and thecontracted position. A number of methods, according to the teachings ofthis embodiment of the present invention, for removing vascularocclusion material are provided. One such method comprises the steps of:providing a vascular occlusion material removal device having anexpandable occlusion material removal element, wherein the removalelement comprises a plurality of braided wires, further comprising anabrasive disposed on the wires; providing a drive shaft disposed in andshiftable with respect to the removal element; intravascularlypositioning the removal element distally of the occlusion material;shifting the drive shaft with respect to the removal element to expandthe element intravascularly; and moving the removal element proximallywithin the vascular lumen to remove occlusion material. The removalelement can also be moved distally within the vascular lumen to engagethe occlusion material. Also, removed occlusion material can becollected by a collection portion on the removal element.

In another embodiment of the present invention, dual coaxial driveshafts are employed. An outer drive shaft is operatively connected tothe proximal end of the expandable material removal element and an innerdrive shaft is operatively connected to the distal end of the expandablematerial removal element. The inner drive shaft and the outer drive areshiftable with respect to one another for moving the removal elementbetween the expanded position and the contracted position. An outersheath surrounds a portion of the coaxial inner and outer drive shaftssuch that the drive shafts and the removal element are rotatable andshiftable with respect to the outer sheath. It is contemplated that theentire assembly including the inner drive shaft, outer drive shaft, andthe outer sheath can be used in conjunction with a standard guidecatheter.

A number of methods, according to the teachings of the dual drive shaftembodiment of the present invention for removing vascular occlusionmaterial are provided. One such method for operating this embodiment ofthe present invention comprises the steps of: providing a vascularocclusion material removal device having an expandable occlusionmaterial removal element, wherein the removal element comprises aplurality of braided wires, further comprising an abrasive disposed onthe wires; providing two coaxial drive shafts wherein an inner driveshaft is operatively coupled to a distal end of the removal element andan outer drive shaft is operatively coupled to the proximal end of theremoval element and wherein the two drive shafts are shiftable withrespect to one another for moving the material removal element betweenthe expanded position and the contracted position; intravascularlypositioning the removal element distally of the occlusion material;shifting the drive shafts with respect to one another causing theremoval element to expand intravascularly; and moving the removalelement proximally within the vascular lumen to remove occlusionmaterial. The removal element can also be moved distally within thevascular lumen to engage the occlusion material. Also, removed occlusionmaterial can be collected by a collection portion on the removalelement.

The present invention describes a number of embodiments of improvedremoval elements. One embodiment of the removal element of the presentinvention includes a plurality of individual wires in a "multi-ended"configuration to increase the abrasive surface area of the removalelement. In this "multi-ended" configuration, a plurality of wires arebundled together to form a multi-ended strand. A plurality ofmulti-ended strands are then braided together and an abrasive isdisposed thereon to form the removal element.

Another embodiment of the removal element of the present inventioncomprises a plurality of braided strands having an abrasive disposedthereon wherein each strand is individually radially wrapped with asecond "wrapping" wire. One advantage of the exemplary embodiment isthat primary braid wire 340 may be manufactured from a material withadvantageous properties to enhance proper expansion and contraction ofremoval element 252 while wrapping wire 342 may be made from a materialwhich readily accepts an abrasive 344. In addition, primary braid wire340 may continually be expanded and contracted as removal element 252 isexpanded and contracted and therefore primary braid wire 340 mayexperience some stress. As a result, abrasive coating 344 placed thereonmay become fatigued after prolonged use. Wrapping wire 342, on the otherhand, is in a coil configuration around primary braid wire 340 andtherefore may not experience the same level of stress as primary braidwire 340. Therefore, abrasive coating 344 placed thereon may then remainin tact despite prolonged use.

BRIEF DESCRIPTION OF THE DRAWINGS

The organization and manner of the structure and operation of theinvention, together with further advantages thereof, may best beunderstood by reference to the following description taken in connectionwith the accompanying drawings, wherein like reference numerals identifylike elements in which:

FIG. 1 is a partially sectioned side elevational view of an expandablevascular occlusion material removal device;

FIG. 2 is an enlarged partially sectioned side elevational view of aproximal portion of the occlusion material removal device of FIG. 1;

FIG. 3 is a view, similar to that of FIG. 2, of an alternativeembodiment of the proximal portion of the occlusion material removaldevice of FIG. 1;

FIG. 4 is an enlarged, partially sectioned side elevational view of adistal portion of the occlusion material removal device of FIG. 1showing an expandable material removal element in a contracted position;

FIG. 5 is a view, similar to that of FIG. 4 illustrating the expandablematerial removal element in an expanded position;

FIG. 6 is an enlarged, partially sectioned side elevational view of analternative embodiment of the distal portion of the removal device ofFIG. 1;

FIG. 7 is a view, similar to that of FIG. 6, of another embodiment ofthe distal portion;

FIG. 8 is a view, similar to that of FIG. 7, of an additional embodimentof the distal portion;

FIG. 9 is a view, similar to that of FIG. 8, of yet a further embodimentof the distal portion;

FIG. 10 is a view, similar to that of FIG. 1, of another embodiment ofthe expandable occlusion material removal device having a dilatingmember at a distal portion thereof;

FIG. 11 is a sectional view of an expandable occlusion material removalelement disposed within an occluded vascular lumen showing theconformity of the removal element to the non-occluded lumen;

FIG. 12 is a sectional view of yet another embodiment of an expandableocclusion material removal device with the removal element in anexpanded position;

FIG. 13 is an enlarged sectional view of a distal end of the removaldevice of FIG. 12 showing the removal element in a contracted position;

FIG. 14 is a view, similar to that of FIG. 13, illustrating the removalelement in an expanded position;

FIG. 15 is a sectional view of the removal element of FIG. 14 in acontracted position forming a pilot hole through an occlusion within avascular lumen;

FIG. 16 is a view, similar to that of FIG. 15, showing the removalelement expanded against the occlusion; and

FIG. 17 is a sectional view of an alternative embodiment of a vascularocclusion material removal device expanded distally of an occlusion andmoved towards the occlusion to remove occlusion material.

FIG. 18 is a side view of another embodiment of an expandable vascularocclusion material removal device.

FIG. 19 is a partial sectioned side elevation view of another embodimentof an expandable vascular occlusion material removal device 250.

FIG. 20 is an enlarged sectional view of FIG. 19 showing the details ofthe drive assembly 283 of an exemplary embodiment of the presentinvention.

FIG. 21 is a sectional view along lines 21 of FIG. 18.

FIG. 22 is a sectional view of another embodiment of a vascularocclusion material removal device.

FIG. 23 is an enlarged side elevational view of an exemplary embodimentof expandable removal element 252.

FIG. 24 shows a cross-section of one strand within the braid ofexpandable removal element 252 containing three wires per strand.

FIG. 25 is an enlarged side elevational view of an exemplary embodimentof expandable removal element 252.

FIG. 26 shows an expandable view of an exemplary embodiment of onestrand 351 within the braid pattern of removal element 252.

FIG. 27 is an enlarged partially-sectioned side elevational view of thedual drive shaft embodiment of the present invention.

FIG. 28 is an expanded partial sectional side view of another embodimentof the inner drive shaft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the invention may be susceptible to embodiment in different forms,there are shown in the drawings, and herein will be described in detail,specific embodiments with the understanding that the present disclosureis to be considered an exemplification of the principles of theinvention, and is not intended to limit the invention to that asillustrated and described herein.

The various embodiments of the present invention provide a number ofconstructions of expandable vascular occlusion material removal devices,intravascular material removal elements, and the like, which can beutilized to perform a plurality of different intravascular treatments,such as atherectomy, thrombectomy, angioplasty and the like. Theembodiments of the present invention also provide a plurality of methodsfor using those devices and their associated vascular occlusion materialremoval elements for performing intravascular treatments on a patient.It is to be fully recognized that the different teachings of thebelow-discussed embodiments can be employed separately or in anysuitable combination to produce desired results. The embodimentsprovide, in the form of expandable intravascular removal elements, waysof changing cutting or removing profiles, configurations orcharacteristics of a particular intravascular treatment device whileonly using a single removal element.

Referring initially to FIG. 1, an expandable intravascular occlusionmaterial removal device 10 is illustrated. The removal device 10generally comprises a drive assembly 12, a catheter assembly 14, and anexpandable material removal element 16 located at a distal end 18 of thecatheter assembly 14. A proximal end 20 of the catheter assembly 14 isconnected to a manifold assembly 22 which forms a connection between thedrive assembly 12 and the catheter assembly 14.

The constructions of the drive assembly 12 and the manifold assembly 22are more clearly shown in FIGS. 1 and 2. The drive assembly 12 generallycomprises an electric motor 24 having a hollow, rotatable drive shaft26, a power source 28, illustrated as a plurality of batterieselectrically connected in series, for energizing the motor 24, and acontrol switch 30 connected electrically between the motor 24 and thepower source 28 such that actuation of the control switch 30 allowscurrent to flow between the power source 28 and the motor 24, therebycausing the drive shaft 26 to rotate. In an exemplary embodiment of theinvention, the motor 24 is a direct current micro-motor available fromMicro Mo Electronics, Inc. of St. Petersburg, Fla., series number2233-04.5S, and the power source 28 is a pair of 3 Volt lithiumbatteries. The motor 24 can rotate the drive shaft 26 at a speed ofabout 10,000 revolutions per minute, but it is envisioned that greaterspeeds, on the order of 100,000 revolutions per minute may be possiblewith different motors 24. For example, the motor 24 may be similar tothe brushless direct current motor available from Transicoil Inc. ofValley Forge, Pa., model number U-222285, which can reach speeds of100,000 revolutions per minute. By rotating the drive shaft 26 at thisspeed, more efficient removal of occlusion material may be achievedbecause the intravascular treatment may take less time. Thus, theremoval device 10 can operate at speeds substantially within the rangeof 0 to 100,000 revolutions per minute. As FIG. 1 shows, the drive shaft26 extends through the motor 24 with a proximal end 32 thereofprojecting from a proximal end of the motor 24, and with a distal end 34thereof extending out of an aperture 38 located on a distal end of ahousing 36 which contains elements of the drive assembly 12. Thesignificance of this structure will become clear later.

An inner hollow tube or sheath 40 is located between an inner, proximalend of the housing 36 and the proximal end of the motor 24 such that theproximal end 32 of the drive shaft 26 extends into the hollow interiorof the inner sheath 40. The inner sheath 40 defines a lumen 46 ofdimensions sufficient for accepting a medical guidewire 42, made ofstainless steel, nitinol, and the like, which can extend from theguidewire lumen 46 within the inner sheath 40, and through an aperture44 in the proximal end of the housing 36 to the exterior of the housing36. Because the drive shaft 26 of the motor 24 is hollow, the guidewire42 can pass through the catheter assembly 14, into the manifold assembly22 and into the drive shaft 26. A fluid seal 43, such as a diaphragm andthe like, is provided at the proximal end 32 of the drive shaft 26 sothat fluid within the drive shaft 26 cannot leak into the interior ofthe housing 36. However, the fluid seal 43 is of appropriateconstruction to allow the guidewire 42 to extend from the drive shaft 26into the inner sheath 40.

The distal end 34 of the drive shaft 26 of the motor 24 is fixedlyconnected to a hollow drive shaft 92 which extends axially through thecatheter assembly 14 and is connected to the material removal element16. In an exemplary embodiment, the drive shaft 92 has an outer diameterof about 0.025". The hollow drive shaft 92 also defines a guidewirelumen, thereby allowing for passage of the guidewire 42 from thematerial removal element 16 to the exterior of the housing 36. Thus, theremoval device 10 is of an over-the-wire construction which canfacilitate removing the device 10 from, and replacing the device 10 inthe patient because the guidewire 42 can remain within the patient.Comparatively, some prior art devices require removal of the guidewirealong with the device, thereby necessitating additional intravascularnavigation not only of the device, but also of the guidewire to replacethe device adjacent the occlusion material to be removed. In addition,the presence of the guidewire 42 facilitates intravascular navigation ofthe removal device 10, because the device 10 can be delivered over theguidewire 42, which is an improvement over some expandable intravasculardevices.

The guidewire 42 is also axially shiftable with respect to the driveassembly 12 and the catheter assembly 14 so that shifting of theguidewire 42 induces corresponding movement of the material removalelement 16 between a contracted position (FIG. 4) and an expandedposition (FIG. 5). This operation will be discussed in greater detailhereinbelow. The guidewire 42 must have sufficient strength to transmitforce to the material removal element 16 to cause movement between thecontracted and expanded positions. This is an important distinction fromsome prior art devices which require a mechanism in addition to amedical guidewire to expand an element intravascularly. Thus, theexpandable intravascular occlusion material removal device 10 is of aconstruction substantially simpler than some of the prior art devices. Avariable length of the guidewire 42 can be shifted distally of theremoval element 16 for facilitating intravascular navigation of theremoval device 10. In an exemplary embodiment of the removal device 10,the guidewire 42 has an outer diameter measuring substantially withinthe range of 0.010" to 0.014". Also, the guidewire 42 may be coated witha low friction coating, such as a nickel-silver alloy like nikasil, or afluoropolymer infused nickel substance like nedox, for reducing frictionbetween the guidewire 42 and the removal device 10.

Because axial shifting of the guidewire 42 causes expansion orcontraction of the material removal element 16, the drive assembly 12includes structures for providing a treating physician with positivecontrol over axial movement of the guidewire 42. Specifically, as shownin FIG. 2, the drive assembly 12 includes a guidewire lock mechanism 50and a material removal element expansion control mechanism 52, both ofwhich serve to positively control expansion or contraction of thematerial removal element 16 by controlling axial shifting of theguidewire 42. The guidewire lock mechanism 50 holds the guidewire 42fixed with respect to itself and to the control mechanism 52 whichallows a treating physician to positively axially shift the guidewire 42and the guidewire lock mechanism 50 by actuation of the expansioncontrol mechanism 52, as will be discussed in greater detail later.

The guidewire lock mechanism 50 is located at a proximal end of thehousing 36 adjacent the aperture 44. The guidewire lock mechanism 50 mayfunction substantially similarly to a pin vise, and comprises a wirelock knob 54 and an inner collet 56, shown in section in FIG. 2, throughwhich the guidewire 42 passes. The wire lock knob 54 and the innercollect 56 are disposed at a proximal end of an outer hollow tube orsheath 58 which also passes through the aperture 44 into the interior ofthe housing 36. The outer sheath 58 accepts the guidewire 42 and alsothe inner sheath 40. The outer sheath 58 is axially shiftable withrespect to the inner sheath 40, and slides along an outer surface of theinner sheath 40, which remains fixed within the housing 36, responsiveto actuation of the expansion control mechanism 52, as will be discussedbelow.

A portion of the inner collet 56 extends into the interior of the outersheath 58 where that portion can engage an outer diameter surface of theguidewire 42. The wire lock knob 54 is rotatable with respect to theinner collet 56 and the outer sheath 58, and is threaded variably ontothe proximal end of the outer sheath 58. Thus, as the wire lock knob 54is appropriately rotated with respect to the inner collet 56 and theouter sheath 58, the wire lock knob 54 moves distally along the outersheath 58 by means of the threaded engagement therebetween, which forcesthe inner collet 56 to engage the outer surface of the guidewire 42. Thewire lock knob 54 is rotated on the outer sheath 58 sufficiently tocompress the inner collet 56 against the guidewire 42 such that theguidewire 42 is fixed with respect to the guidewire lock mechanism 50and the outer sheath 58. However, the outer sheath 58 is axiallyshiftable with respect to the inner sheath 40, the motor 24 and thedrive shaft 26 responsive to actuation of the expansion controlmechanism 52. Thus, the guidewire 42 is also positively shiftableresponsive to movement of the control mechanism 52. Proper applicationof the guidewire lock mechanism 50 to the guidewire 42 allows aphysician to positively vary expansion and/or contraction of theexpandable material removal element 16. To release the guidewire 42 fromthe grip of the inner collet 56 and the wire lock mechanism 50, the wirelock knob 54 is rotated in an opposite direction, thereby allowing aportion of the inner collet 56 to move out of the outer sheath 58, andout of engagement with the outer surface of the guidewire 42.

The material removal element expansion control mechanism 52 isoperatively connected to the outer sheath 58 such that actuation of thecontrol mechanism 52 causes conjoint motion of the outer sheath 58 andthe guidewire 42, which causes expansion and/or contraction of thematerial removal element 16 (assuming that the wire lock mechanism 50holds the guidewire 42 fixed with respect to the control mechanism 52and the outer sheath 58). Specifically, the material removal elementexpansion control mechanism 52 comprises a shaft 60 extendingsubstantially perpendicularly from the inner sheath 40 and the outersheath 58 through an elongate slot 62 in the housing 36. One end of theshaft 60 is connected to a shoulder portion 64 located adjacent a distalend of the outer sheath 58 by a compressible spring 65. The spring 65biases the shaft 60 away from the outer sheath 58. An opposite end ofthe shaft 60 extends out of the housing 36 through the slot 62 where itis connected to a thumb pad 66. The thumb pad 66 is configured forfacilitating application of a force from a treating physician's thumb toinduce axial shifting of the guidewire 42, and thus, correspondingexpansion and/or contraction of the expandable material removal element16.

Means is provided within the housing 36 to facilitate positive shiftingof the guidewire 42, and also positive movement of the expandablematerial removal element 16 between the expanded and contractedpositions. Specifically, in the illustrated embodiment, a first set ofteeth 68 is attached to the shaft 60 such that the teeth 68 extendperpendicularly with respect to an axis of elongation of the shaft 60and substantially parallel with respect to an adjacent portion of thehousing 36. Because the shaft 60 can move against the spring 65 underthe influence of forces applied to the thumb pad 66, the first set ofteeth 68 is also movable in corresponding fashion. A second set of teeth70 depend from the interior surface of the housing 36 adjacent the slot62 such that the first set of teeth 68 is interengagable with the secondset of teeth 70. The second set of teeth 70 is fixed with respect to thehousing 36 such that, when the teeth 68 and 70 are interengaged, theouter sheath 58 is fixed with respect to the housing 36. This preventsaxial shifting of the guidewire 42 with respect to the drive assembly12, the catheter assembly 14, and the removal element 16 if theguidewire lock mechanism 50 is applied.

The structure of the guidewire lock mechanism 50 and the materialremoval element expansion control mechanism 52 may be more readilyunderstood with reference to the following discussion of the operationthereof. The guidewire 42 is disposed through the drive shaft 26, themotor 24, the inner sheath 40, the outer sheath 58, the inner collet 56and the wire lock knob 54. The wire lock knob 54 is rotated with respectto the outer sheath 58 such that threads on the lock knob 54 and theouter sheath 58 cooperate to cause distally directed movement of thelock knob 54 with respect to the outer sheath 58. Distally directedmovement of the lock knob 54 forces the inner collet 56 progressivelyfurther into the interior of the outer sheath 58. As the inner collet 56moves into the outer sheath 58, a portion of the inner collet 56 withinthe outer sheath 58 engages an outer surface of the guidewire 42. Thewire lock knob 54 is rotated on the outer sheath 58 so that the portionof the inner collet 56 engages the outer surface of the guidewire 42with sufficient force to hold the guidewire 42 fixed with respect to theouter sheath 58 and the guidewire lock mechanism 50. The guidewire 42,the guidewire lock mechanism 50 and the outer sheath 58 now moveconjointly.

A treating physician applies an appropriate force to the thumb pad 66,thereby causing movement of the shaft 60 towards the shoulder portion 64of the outer sheath 58 and compressing the spring 65 between an end ofthe shaft 60 and the shoulder portion 64 of the outer sheath 58.Sufficient movement of the shaft 60 towards the shoulder portion 64 andsufficient compression of the spring 65 disengages the teeth 68 from theteeth 70 because the teeth 68 move conjointly with the shaft 60 whilethe teeth 70 remain fixed. The treating physician can now apply forcesto the thumb pad 66 to conjointly axially shift the guidewire 42, theouter sheath 58, the guidewire lock mechanism 50 and the materialremoval element expansion control mechanism 52.

Specifically, the treating physician can apply forces to the thumb pad66 to move or shift the guidewire 42 and the outer sheath 58 proximallyrearwardly. This movement, as will be discussed in greater detail later,causes expansion of the material removal element 16. As these forces areapplied to the thumb pad 66, those forces are transmitted to theshoulder portion 64 of the outer sheath 58. The outer sheath 58 slidesproximally along the outer surface of the inner sheath 40 towards theaperture 44 in the housing 36. The range of sliding motion of the outersheath 58 along the inner sheath 40 is limited by engagement of aproximal end of the teeth 68 with the adjacent interior surface of thehousing 36, as well as by the dimensions of the elongate slot 62 inwhich a portion of the shaft 60 moves conjointly with the outer sheath58.

The degree of material removal element 16 expansion is directlyproportional to the length of axial shifting of the guidewire 42 and theouter sheath 58 proximally. Thus, the degree of material removal element16 expansion and/or contraction can be measured by suitable scalingmeans 59 or 79 disposed on the housing 36 adjacent the elongate slot 62.When a desired degree of material removal element 16 expansion has beenachieved, the thumb pad 66 can be released. The spring 65 now expandsand forces the teeth 68 into engagement with the teeth 70.Interengagement of the teeth 68 and 70 positively locks the axialposition of the guidewire 42, and thus, also the expanded position ofthe material removal element 16. Because a plurality of teeth 68 and 70are provided, the material removal element expansion control mechanism52 allows for positively controlled, incremental expansion of thematerial removal element 16. To contract the expandable material removalelement 16, the above-discussed steps are repeated, but this time, thetreating physician moves the thumb pad 66 and the guidewire 42 distally.

An alternative embodiment of the material removal element expansioncontrol mechanism 52 is illustrated in FIG. 3. It is to be noted thatthe construction of this embodiment is substantially similar to thatillustrated in FIGS. 1 and 2, except for the differences notedhereinbelow, hence the like reference numerals for similar structures.The guidewire lock mechanism 50 of the embodiment of FIG. 2 is the sameas that of the embodiment of FIG. 3.

Specifically, in the embodiment of FIG. 3, the material removal elementexpansion control mechanism 52 comprises an expansion knob 72 and athreaded hub 74. The threaded hub 74 extends from and is fixed to aproximal end of the housing 36 and surrounds the aperture 44 in thehousing 36 and the outer sheath 58. The expansion knob 72 has internalthreads matable with the threads on the threaded hub 74, and is disposedon the hub 74 such that the knob 72 surrounds the hub 74. The expansionknob 72 is rotatable on the threaded hub 74, and the threads thereoncooperate so that rotation of the expansion knob 72 on the threaded hub74 causes the expansion knob 72 to move proximally or distally withrespect to the hub 74, depending upon the direction of rotation. Distalmovement of the expansion knob 72 causes contraction of the materialremoval element 16 and proximal movement of the expansion knob 72 causesexpansion of the material removal element 16.

To expand the material removal element 16, the expansion knob 72 isrotated such that the knob 72 moves proximally on the threaded hub 74 sothat a proximal end 76 of the expansion knob 72 contacts a distal end ofthe wire lock knob 54. Further proximal motion of the expansion knob 72forces the wire lock knob 54 to shift proximally with respect to thedrive assembly 12, thereby shifting the guidewire 42 proximally as well.The outer sheath 58 conjointly slides proximally along the outer surfaceof the inner sheath 40, as discussed above. Proximal movement of theexpansion knob 72 on the threaded hub 74 is positively limited, therebylimiting the maximum size of the expandable material removal element 16.Specifically, upon sufficient rotation and proximal movement of theexpansion knob 72, a proximal end of the shoulder portion 64 engages aninterior proximal side of the housing 36.

The expandable material removal element 16 can be contracted byreversing the direction of rotation of the expansion knob 72. Tofacilitate return of the material removal element 16 from the expandedposition to the contracted position, a coiled spring 77 may be disposedbetween the shoulder portion 64 and the proximal end of the motor 24, asshown in FIG. 3, or, alternatively, disposed between the shoulderportion 64 and the proximal end of the housing 36. The spring 77 relaxesas the expansion knob 72 moves distally on the threaded hub 74.Relaxation of the spring 77 moves the outer sheath 58, the wire lockknob 54 and the guidewire 42 proximally with respect to the driveassembly 12. Suitable scaling means 59 or 79 can be provided on theexpansion knob 72 and/or the housing 36 for providing a treatingphysician with a positive indication of the degree of expansion and/orcontraction of the expandable material removal element 16.

The construction of the manifold assembly 22 is illustrated in FIGS. 1through 3. The manifold assembly 22 connects the drive assembly 12 tothe catheter assembly 16. The manifold assembly 22 generally comprises amain lumen 78 which extends from a distal end of the housing 36 to theproximal end 20 of the catheter assembly 14, and has at least two ports80 and 82, accessible from the exterior of the manifold assembly 22,which communicate with the main lumen 78. The hollow drive shaft 26 ofthe motor 24 extends through the aperture 38 in the housing 36 and intothe main lumen 78. The drive shaft 26 has a lumen therein of dimensionssufficient for accepting the guidewire 42 so that the guidewire 42 canalso extend into the main lumen 78 within the drive shaft 26.

In the illustrated embodiment, the drive shaft 26 extends into the mainlumen 78 a distance sufficient to locate the distal end 34 of the driveshaft 26 distally of the port 80. A pair of fluid seals 84 and 86 areprovided within the main lumen 78 on opposite sides of the port 80. Thefluid seals 84 and 86 extend from the main lumen 78 to an outer surfaceof the drive shaft 26 and form a fluid-tight seal around a portion ofthe drive shaft 26 therebetween. A longitudinal aperture 88 is locatedon the drive shaft 26 between the fluid seals 84 and 86 for allowingfluid to pass into the hollow interior of the drive shaft 26. Thisconstruction allows the port 80 to be dedicated to infusion of fluidsinto the drive shaft 26. This infused fluid can provide for increasedlubrication between the outer surface of the guidewire 42 and the innersurface of the drive shaft 26, which may be beneficial during operationof the motor 24, and for allowing irrigation of an intravasculartreatment site, which may be necessary to maintain a fluid balancewithin a vascular lumen if aspiration techniques are also used.Accordingly, the port 80 is connectable to a suitable fluid source, notshown, but well known in the art. The port 82 can be utilized forinfusion of fluids, such as contrast media, saline, a drug therapy, andthe like, into the patient, and for aspiration of the intravasculartreatment site. The fluid seals 84 and 86 provide for this independentoperation of the ports 80 and 82, and also insure that fluids introducedinto the main lumen 78 will not reach the motor 24. To insure deliveryof the fluids for infusion or negative pressures for aspiration, theport 82 communicates with a catheter sheath 90 connected to the distalend of the manifold assembly 22. The catheter sheath 90 is of well knownconstruction, and can be made from polyethylene, KYNAR, a fluoropolymerand the like. In an exemplary embodiment, the catheter sheath 90 canhave an axial length of about 133 cm and an outer diameter of about0.072", thereby enabling it to be inserted into a 7 French guidecatheter. The proximal end of the catheter sheath 90 defines theproximal end 20 of the catheter assembly 14.

The distal end 34 of the hollow drive shaft 26 is fixedly attached toanother hollow drive shaft 92, which extends through the catheter sheath90 of the catheter assembly 14, so that the drive shafts 24 and 92rotate conjointly. The construction of the drive shaft 92 is illustratedin FIGS. 4 and 5. Specifically, the drive shaft 92 comprises an innercoil 94, preferably formed from a plurality of intertwined strands of awire composed of a suitable metal, such as stainless steel or nitinol,wound in a predetermined direction such that the coil 94 expandsradially upon rotation of the drive shaft 92. This maintains orincreases the clearance between the outer surface of the guidewire 42and the inner surface of the coil 94. In order to limit radial and axialexpansion of the inner coil 94, a wire braid 96, formed from a metalsuch as stainless steel, nitinol or the like, is applied over a portionof the outer diameter surface of the coil 94. Wires forming the innercoil 94 and the braid 96 can have a rounded or flattened configuration.

An end of the braid 96 is applied over the outer diameter surface of thecoil 94 and attached by suitable means, such as solder, braze, and thelike, to a proximal end of the inner coil 94. The braid 96 is thenstretched axially or tensioned along the length of the inner coil 94,thereby closely confining radial expansion of the individual windings ofthe inner coil 94. Once stretched, an end of the braid 96 is attached toa portion of the inner coil 94 preferably offset proximally of a distalend 98 of the inner coil 94. This, in the illustrated embodiment, leavesa number of distal-most windings of the inner coil 94 uncovered by thebraid 96, however, it is to be understood that the braid 96 can extendalong the entire axial length of the coil 94 or may be entirelyeliminated.

Tensioning the braid 96 over the outer diameter surface of the innercoil 94 limits the radial expansion of the coil 94 during operation ofthe motor 24. In addition, by covering the proximal portion of the innercoil 94 with the braid 96, the drive shaft 92 has an increased torquerigidity as compared to the coil 94 alone. Torque transfer to theexpandable material removal element 16 is correspondingly increased, andthe distal end 98 of the inner coil 94 is more responsive to proximallyapplied torques. Furthermore, by leaving a distal-most portion of thecoil 94 uncovered by the braid 96, that portion is rather flexible andhas increased trackability, thereby making it easier to torque thedistal end 98 through tight curves within a patient's vasculature. Tofurther improve trackability, as well as to reduce friction between theouter surface of the drive shaft 92 and the inner surface of thecatheter sheath 90, a lubricous or low friction coating 100, comprisedof a fluoropolymer and the like, is applied to the outer surface of thedrive shaft 92. The coating 100 may be provided in the form of a sheathof a fluoropolymer which shrinks upon application of heat. In thismanner, the coating 100 can reduce friction between the drive shaft 92and the coating 100, provide the drive shaft 92 with increased torsionalrigidity, limit radial expansion of the drive shaft 92, and form afluid-tight lumen through the drive shaft 92. The coating 100 can alsoinsure proper aspiration through the catheter sheath 90 by minimizingfriction between the drive shaft 92 and occlusion material aspiratedinto the catheter sheath 90. Also, as shown in FIGS. 1, 4 and 5, thecatheter sheath 90 terminates at a location offset proximally of thedistal end 98 of the drive shaft 92 and a proximal end of the materialremoval element 16. This provides for proper irrigation and aspirationof an intravascular treatment site because the irrigation site islocated distally of the aspiration site.

In some embodiments, the drive shaft 92 may not include the braid 96. Inthese embodiments, the inner coil 94 of the drive shaft 92 is formed bywires wound opposite to the intended direction of rotation of the driveshaft 92. In this manner, the coil 94 may radially expand upon rotationof the drive shaft 92. Another coil, formed by wires wound in theintended direction of drive shaft 92 rotation surrounds the inner coil94. Because this outer coil is wound in the direction of drive shaft 92rotation, the outer coil may radially contract upon rotation of thedrive shaft 92. The radial expansion of the inner coil 94 is balanced bythe radially contraction of the outer coil. Thus, the outer coil canperform substantially the same function as the braid 96. Someembodiments of the drive shaft 92 may axially expand or contractresponsive to radial contraction or expansion, respectively, thereofduring operation of the removal device 10. The drive shaft 92 may beconstructed, by appropriately winding the inner and outer coils, torender axially expansion and/or contraction of the drive shaft 92controllable. The axial expansion or contraction of the drive shaft 92may also effect radial expansion of the removal element 16. This will bediscussed further later.

The distal end 98 of the inner coil 94 is fixedly attached to theexpandable material removal element 16 so that the drive shaft 92 andthe material removal element 16 rotate conjointly. The material removalelement 16 generally comprises a plurality, preferably 8 or 16, ofbraided wires 102. The wires 102 themselves preferably have asubstantially round latitudinal cross section defining an outer diameterof about 0.002" to 0.006", although wires having flat, square, ortriangular cross sections can also be used. In an exemplary embodimentof the removal element 16, the wires 102 comprise nitinol super-elasticwire, chromium-doped as drawn, having a diameter of about 0.003". Inthis embodiment, 16 nitinol wires 102 are braided at about 80 to 120pics per inch and heat set at approximately 500 degrees Celsius forabout 5 minutes. This embodiment of the removal element 16 has a lengthsubstantially within the range of about 1 cm to 3 cm, a contracteddiameter substantially within the range of 1 mm to 1.125 mm, and amaximum expanded diameter of about 4 mm. In another exemplaryembodiment, the wires 102 define a removal element 16 having an axiallength of about 1.5 cm, and an outer diameter of about 1.25 mm in thecontracted position. In the fully expanded position, this otherembodiment of the removal element 16 can define an outer diametermeasuring substantially within the range of 2.0 to 4.0 mm.

The outer surfaces of the wires 102 may be sharpened, etched or coatedwith an abrasive 105, such as a diamond grit and the like, to improvethe removing or cutting characteristics of the material removal element16. In one embodiment, a diamond grit having a grit size substantiallywithin the range of 5 to 100 microns is electroplated onto the wires 102in substantially uniform manner, however, the grit may be asymmetricallydeposited on the wires 102 if desired. In another exemplary embodiment,the abrasive 105 may comprise a diamond grit or synthetic abrasive, suchas a cubic boron nitride and the like, having a grit size approximatelywithin the range of 10 to 25 microns, attached to the wires 102 by anickel electroplating process. The disposition of the abrasive 105 onthe wires 102 may depend upon the particular embodiment of the vascularocclusion material removal device.

In some embodiments, after the wires 102 are coated with the abrasive105, a radiopaque material, such as gold, platinum, a radiopaque ink andthe like, may be placed over the abrasive coated wires 102 to render theremoval element 16 radioscopically visible. In still other embodiments,the abrasive coated wires 102 may be further coated with a low frictionsubstance, such as nickel, a nickel plating infused with a fluoropolymerand the like. If nickel is used, a well known electroless platingprocess may be used to apply the nickel to the removal element 16. If afluoropolymer infused nickel plating, such as nedox, is used, then thisplating may be applied to the removal element 16 by the processperformed by General Magnaplate Texas of Arlington, Tex. Otherembodiments of the removal element 16 may not include an abrasive 105.In these embodiments, the wires 102 may be substantially ribbon-like inconfiguration. These ribbon-like wires are axially twisted and thenbraided to form the removal element 16. The edges of the twistedribbon-like wires act substantially similarly to the abrasive 105 toremove occlusion material.

The wires 102 are preferably made from a super-elastic or shape memorymetal alloy, such as nitinol and the like, which allows the wires 102 torecover strains greater than those recoverable by other metals. Thisincreased strain recovery allows the wires 102 to resist permanentdeformation during repeated expansions and contractions as well asduring contact with vascular occlusion material. The use ofsuper-elastic alloys for the wires 102 facilitates return of thematerial removal element 16 to its original low profile, contractedcondition, which also makes intravascular navigation of the materialremoval element 16 easier and facilitates retention of vascularocclusion material within the material removal element 16. In anexemplary construction, the expandable material removal element 16 andthe catheter assembly 14 as a whole have a sufficiently low profile toallow insertion of the catheter assembly 14 and the material removalelement 16 through a conventional 7 French guide catheter.

A proximal annulus 104 is attached to the distal end 98 of the innercoil 94 by suitable means, such as an adhesive, solder, braze or a weld,and the proximal ends of the braided wires 102 are attached to the outersurface of the proximal annulus 104 by similar means. Thus, the braidedwires 102 comprising the material removal element 16 rotate conjointlywith the drive shafts 26 and 92 and the proximal annulus 104 under theinfluence of forces generated by the motor 24. The distal ends of thewires 102 are attached to a distal annulus 106, which may be made of ametal. In an exemplary embodiment, the distal annulus 106 is a hypotube,such as a 304 stainless steel 21XX hypotube available from Micro Group,Inc. of Medway, Mass., and the wires 102 are brazed to the distalannulus 106 with a Turbo braze paste available from Turbo BrazeCorporation of Union, N.J. The wires 102, proximal annulus 104, and thedistal annulus 106 are radioscopically visible when the wires 102 areattached to the annuluses 104 and 106. The distal annulus 106 isprovided with a cutting surface 108 located distally of the point ofattachment of the wires 102. The cutting surface 108 may also be coatedwith an abrasive 105, such as the diamond grit or synthetic abrasivedisclosed earlier.

The braided wires 102 of the material removal element 16 define a hollowinterior which can ingest or capture vascular occlusion material, aswill be discussed in greater detail below. Abrasive 105 on the portionsof the wires 102 facing the hollow interior may facilitate retention ofthe captured occlusion material within the hollow interior. In addition,the dimensions of the hollow interior are sufficient to accept a distalportion of the guidewire 42. Specifically, an aperture 110 is providedin the distal annulus 106 so that the guidewire 42 can be insertedtherethrough and into the hollow interior of the material removalelement 16. From there, the guidewire 42 can be inserted through theproximal annulus 104 into the hollow drive shaft 92, the drive shaft 26,the motor 24, and through the inner sheath 40, the outer sheath 58, andthe guidewire lock mechanism 50. To traverse this distance, theguidewire 42 may be of a length suitable for facilitating removal andreplacement of the device 10 within a patient, or may be extendable, andmay be coated with a lubricous or a low friction substance, such as afluoroploymer or a fluoropolymer-loaded nickel plating, to facilitateforce transfer from the guidewire 42 to the distal end of the materialremoval element 16. The removal device 10 can also be exchangedintravascularly according to the methods disclosed in the co-pendingU.S. patent application of Mazzola et al., Ser. No. 07/789,183, filed onNov. 8, 1991. That application is assigned to the assignee of thepresent invention, and the disclosure thereof is incorporated herein byreference.

A distal end of the guidewire 42 includes a bearing surface 112, whichcan have one of several embodiments (FIGS. 6 through 9), which isfixedly attached to the guidewire 42. For example, the bearing surface112 may be a short tube, a bearing or a bead 120 (FIG. 6) slipped ontothe guidewire 42 having a smooth, low friction surface, a braze orsolder fillet 122 (FIG. 7), or may be a centerless ground bump 124 (FIG.8) on the guidewire 42. In some embodiments, the bearing surface 112 maybe coated with a low friction substance, such as a fluoropolymer and thelike. The bearing surface 112 is located at a proximal end of aradiopaque coil 114 which defines a distal-most end of the guidewire 42.The coil 114 may be made from platinum or other suitable substance, and,in an exemplary embodiment, has an axial length of about 3 cm and anouter diameter of 0.014". The dimensions of the bearing surface 112 arelarger than the corresponding dimensions of the aperture 110 in theannulus 106 so that the bearing surface 112 butts up against a distalend of the annulus 106, the significance of which will become more clearlater. For example, the bearing surface 112 may define an outer diameterof about 0.016" and the aperture 110 may define an inner diameter ofabout 0.010" to 0.014". As stated above, the outer diameter surface ofthe guidewire 42 may be coated with a lubricous or low friction coating,such as fluoropolymer, a fluoropolymer-loaded metallic coating, asilicone dispersion, and the like, to minimize friction between theguidewire 42 and the drive shafts 26 and 92. This may be desirablebecause the guidewire 42 remains within the drive shafts 26 and 92 andis secured against axial movement by the wire lock mechanism 50 duringoperation of the occlusion material removal device 10.

With the basic structure of the occlusion material removal device 10being thusly disclosed, a greater appreciation of the construction andbenefits of the expandable material removal element 16 of the device 10may be gained from the following discussion of the operation of thedevice 10. It is to be noted that this discussion is provided forillustrative purposes only.

The guidewire 42 is inserted intravascularly into the patient andnavigated to the intravascular treatment site. If possible, theradiopaque coil 114 may be located through or distally of vascularocclusion material to be removed. A proximal end of the guidewire 42 isinserted through the distal annulus 106, and is guided through the moreproximal portions of the removal device 10 until the distal end of thedistal annulus 106 is proximate to the proximal end of the bearingsurface 112 within the patient's vasculature. This procedure can be usedif the guidewire 42 has sufficient length, i.e. is of exchange length.For shorter guidewires 42, the guidewire 42 can be pre-loaded into theremoval element 16, and then the guidewire 42 and the element 16 can beconjointly inserted into the patient's vasculature. Sufficient length ofthe guidewire 42 can be positioned distally of the removal element 16 tofacilitate intravascular navigation thereof.

The material removal element 16 is inserted into the patient'svasculature over the guidewire 42 while in the contracted positionillustrated in FIG. 4. In an exemplary method of use, the removal device10 is inserted into the patient's vasculature through a guide catheteror an introducer sheath in common fashion. If such a guide is used, thena fluid seal may be provided between the guide catheter and the device10 to limit blood loss from the patient due to axial shifting of thedevice 10 with respect to the guide catheter. Thus, back flow of bloodor other bodily fluids through a lumen between the guide catheter andthe removal device 10 can be limited.

As shown, the axial distance between the distal end 98 of the inner coil94 and the proximal end of the bearing surface 112 can be sufficient toallow the braided wires 102 comprising the material removal element 16to completely axially relax or expand, thereby causing the materialremoval element 16 to contract radially. The proximal end of the bearingsurface 112 may not contact the distal end of the distal annulus 106when the material removal element 16 is in this contracted position.When in the contracted position, the material removal element 16 definesa low profile and an outer diameter slightly larger than the outerdiameter of the drive shaft 92. This low profile facilitatesintravascular navigation of the material removal element 16.

The removal element 16 is positioned adjacent the occlusion material tobe removed. With some embodiments, the coil 114 of the guidewire 42 mayhave to be located across the occlusion, but it is envisioned that otherembodiments may not require this. If the treating physician wishes toshift the material removal element 16 towards the expanded conditionillustrated in FIG. 5, then the physician moves the guidewire 42proximally as described above with reference to the guidewire lockmechanism 50 and the material removal element expansion controlmechanism 52. As the treating physician moves the guidewire 42proximally, the length of the guidewire 42 disposed within the patient'svascular system is reduced. Correspondingly, the axial distance betweenthe bearing surface 112 and the distal annulus 106 decreases until theproximal end of the bearing surface 112 engages the distal end of thedistal annulus 106. The guidewire 42 is moved progressively proximallyand the axial distance between the distal annulus 106 and the distal end98 of the inner coil 94 decreases. The braided wires 102 comprising theexpandable material removal element 16 are axially compressed, therebycausing the material removal element 16 to expand radially.

Once the material removal element 16 is expanded to the desired degree,which can be positively verified by checking the scaling means 59 or 79on the drive assembly 12, the thumb pad 66 of the material removalelement expansion control mechanism 52 is released and now maintains theexpanded position of the material removal element 16. The degree ofexpansion of the removal element 16 may also be positively verified byradioscopic techniques, i.e. if the particular embodiment of the removalelement 16 is radioscopically visible. If the physician wishes toradially contract the material removal element 16, then he moves theguidewire 42 distally, as described hereinabove. By suitablemanipulation of the guidewire 42, the guidewire lock mechanism 50, andthe material removal element expansion control mechanism 52, thematerial removal element 16 can take on a number of differentconfigurations and sizes, thereby changing the cutting profiles orcharacteristics of the material removal element 16 without having toremove the material removal element 16 from the patient's vasculature.This can provide the treating physician with greater flexibility inperforming intravascular treatments, and may possibly reduce the cost ofan intravascular procedure because multiple pieces of equipment need notbe used.

While an expandable intravascular removal element 16 is highly desirablefor the reasons discussed earlier, it may be desirable to limit themaximum size of these intravascular elements 16. It may be desirable notto over-expand the expandable removal elements 16. While some means forpositively limiting radial expansion of the expandable intravascularremoval element 16 have been detailed hereinabove, it may be desirableto provide additional safety mechanisms. For instance, it is to be notedthat the expansion of the material removal element 16 shown in FIGS. 1,4, and 5 is limited by contact between a proximal end 118 of the distalannulus 106 and the distal end 98 of the inner coil 94. The embodimentsof the invention illustrated in FIGS. 6 through 9 provide constructionsof removal element expansion limiting means which are included withinthe expandable elements 16 themselves. In addition, these Figures showsome alternative constructions for the bearing surface 112, as indicatedearlier.

In the construction 116 of FIG. 6, the distal end 98 of the inner coil94 extends through and distally of the proximal annulus 104 and into thehollow interior of the material removal element 16 defined by thebraided wires 102. This is the currently preferred embodiment of thematerial removal element radial expansion limiting means. The distal end98 of the inner coil 94 extends into the interior of the materialremoval element 16 a specific, predetermined distance which limits theradial expansion of the braided wires 102 by a corresponding distance.In other words, the proximal end 118 of the distal annulus 106 of theconstruction 116 can travel a maximum distance smaller than the distancetraveled by the proximal end 118 of the distal annulus 106 of theembodiments of FIGS. 1, 4, and 5 upon maximum proximal movement of thebead 120 and the guidewire 42. Contact between the proximal end 118 ofthe distal annulus 106 and the distal end 98 of the inner coil 94positively limits axial compression and radial expansion of the materialremoval element 16. Once the proximal end 118 engages the distal end 98,the removal element 16 cannot be further axially compressed because theguidewire 42 and the bead 120 cannot be moved further proximally. Thus,the material removal element 16 of the construction 116 can radiallyexpand a predetermined maximum distance smaller than the maximumdistance of radial expansion of the material removal element 16 of theembodiments of FIGS. 1, 4 and 5.

Another construction 126 of the distal portion of the vascular occlusionmaterial removal device 10 is shown in FIG. 7. This construction 126utilizes material removal element radial expansion limiting means in theform of elongated windings 128 on a portion of the inner coil 94 thatextend into the interior of the material removal element 16 in much thesame manner as discussed hereinabove with respect to the construction116. However, in this construction 126, the distal end 98 of the of theinner coil 94 is fixedly attached to the distal annulus 106 by solder,weld, braze or similar means. Thus, when the guidewire 42 is movedproximally and the fillet 122 engages the distal annulus 106, theexpanded windings 128 within the hollow interior of the material removalelement 16 are compressed until adjacent windings 130A and 130B onopposite sides of each of the expanded windings 128 contact each other.In this manner, the axial compression and the radial expansion of thebraided material removal element 16 are positively limited by the sum ofthe distances between the adjacent windings 130A and 130B within theinterior of the material removal element 16 when the material removalelement 16 is in the relaxed, contracted position as shown.

Yet another embodiment of the material removal element radial expansionlimiting means is shown in FIG. 8. Here, the means takes the form of twotubes 132 and 134, such as hypotubes and the like. The tube 132 isfixedly attached to an inner surface of the distal-most windings of theinner coil 94 by suitable means, such as adhesive, solder, braze orweld, and is also attached by similar means to the proximal annulus 104.This insures proper torque transfer from the drive shaft 92 to thematerial removal element 16. The tube 132 extends into the hollowinterior of the material removal element 16 a certain, predetermineddistance to locate a distal end 136 of the tube 132 within the hollowinterior.

The tube 134 is fixedly attached to the distal annulus 106 by similarmeans, and extends proximally into the hollow interior of the materialremoval element 16 to locate a proximal end 138 of the tube 134 withinthe hollow interior. Thus, the distal end 136 of the tube 132 is offsetfrom the proximal end 138 of the tube 134 by a predetermined distancewhich limits axial compression of the radially expandable materialremoval element 16. The tubes 132 and 134 both have inner diameterssufficient for accepting the guidewire 42 therethrough so that thematerial removal element 16 of this embodiment radially expands in thesame manner as the other embodiments. As the guidewire 42 and the bump124 move proximally, the bump 124 engages the distal annulus 106 andforces the distal annulus 106 and the tube 134 proximally. The braidedwires 102 expand radially until the distal end 136 of the tube 132contacts the proximal end 138 of the tube 134. This contact positivelylimits radial expansion of the material removal element 16. Thus, thelengths of both tubes 132 and 134 and the distance between the distalend 136 and the proximal end 138 determine the maximum radial expansionof the material removal element 16.

An additional embodiment of the material removal element radialexpansion limiting means is contained in the construction 140 of FIG. 9.Here, the tube 134 is eliminated and the tube 132 is elongated withrespect to the embodiment of FIG. 8. When the material removal element16 is expanded fully, the proximal end 118 of the distal annulus 106engages the distal end 136 of the tube 132. Thus, the length of the tube132 and the distance between the distal end 136 of the tube 132 and theproximal end 118 of the distal annulus 106 within the hollow interior ofthe material removal element 16 determine and positively limit themaximum radial expansion of the material removal element 16.

In some cases, it may be desirable to perform balloon angioplasty inconjunction with vascular occlusion material removal. Because of thisdesire, another embodiment of the invention, an expandable intravascularocclusion removal device 142, is provided and is shown in FIG. 10. Theremoval device 142 is substantially similar to the removal device 10,except for the differences noted in the following paragraphs, hence thelike reference numerals for similar structures. While the removal device142 is illustrated as having the lock knob 54 and the thumb pad 66, itis to be remembered that the elements of the various embodiments of theinvention can be combined in any desired fashion.

The removal device 142 includes a manifold assembly 144 and a catheterassembly 146 which differ from the catheter assembly 14 and the manifoldassembly 22. Specifically, the manifold assembly 144 includes a thirdport 148 located distally of the port 82. The port 148 is connectablewith a suitable source of fluid, not shown, but known in the art, forsupplying the catheter assembly 146 with fluid to dilate a dilatingmember 158 for performing balloon angioplasty. The port 148 is locateddistally of a proximal end 150 of the catheter assembly 146.

The catheter assembly 146 includes a catheter sheath 152 having at leasttwo lumens: a drive shaft lumen 154 and a fluid inflation lumen 156. Thedrive shaft 92 extends through the drive shaft lumen 154 from the distalend 34 of the drive shaft 26 to the proximal annulus 104, and the driveshaft lumen 154 can be utilized for infusion and aspiration in much thesame manner as the catheter sheath 90 can. The drive shaft lumen 154extends substantially the entire length from the manifold assembly 144to the proximal annulus 104.

A dilating member 158, constructed substantially similarly to anangioplasty balloon, is located on the catheter assembly 146 offsetproximally of a distal end 160 of the catheter assembly 146 and thedistal end of the drive shaft lumen 154. The inflation lumen 156 extendsfrom the port 148 to a proximal end 162 of the dilating member 158 andconveys fluid from the fluid source, conventionally referred to as aninflation device, to and from the dilating member 158, thereby causingthe dilating member 158 to inflate and deflate. To facilitateintravascular location of the dilating member 158, a radiopague markerband 164 is provided on the outer surface of the drive shaft lumen 154,thereby rendering the intravascular portion of the dilating member 158radioscopically visible to a treating physician. Intravascular inflationof the dilating member 158 provides added stability to the distalportion of the removal device 142 during operation thereof, while alsoallowing the treating physician to occlude blood flow through thevascular lumen being treated and further allowing the physician toperform balloon angioplasty if desired. With the removal device 142 itis possible for a treating physician to cut, remove, and/orangioplasticly displace vascular occlusion material while only using asingle piece of equipment.

Yet another embodiment 176 of an expandable intravascular occlusionmaterial removal device is illustrated in FIG. 12. This embodiment 176is substantially similar to the devices 10 and 142 describedhereinabove, except for the differences detailed below, hence the likereference numerals for similar structures. The device 176 uses the samematerial removal element 16 and substantially the same drive assembly 12as described earlier. However, because the device 176 does not use theguidewire 42 to move the removal element 16 between the contracted andthe expanded positions, certain modifications can be made to the driveassembly 12. With the removal device 176, the removal element 16 ismoved between the expanded position of FIG. 14 and the contractedposition of FIG. 13 by axial movement of a catheter assembly 178 withrespect to the drive shaft 92.

The drive assembly 12 comprises the housing 36 containing the motor 24,the power source 28, and the control switch 30. The housing 36 may beformed from a suitable material, such as polycarbonate, polyethylene orthe like. In an exemplary embodiment of the removal device 176, thedrive motor 24 may be a direct current micromotor, such as thosedisclosed hereinabove, which can produce a start up torque of about 2.6ounce-inch and a no-load torque of about 0.015 ounce-inch. The drivemotor 24 may have a speed range of about 5,000 to about 100,000revolutions per minute, with a speed of about 20,000 revolutions perminute being the currently preferred operating speed of the device 176.

The drive motor 24 has the hollow drive shaft 26 so that the guidewire42 can pass therethrough, thereby allowing the removal device 176 to bedelivered over the guidewire 42. In an exemplary embodiment, theguidewire 42 may be substantially similar to guidewires used forpercutaneous transluminal coronary angioplasty, although otherguidewires may also be used. In some embodiments, at least a portion ofthe guidewire 42 may be coated with a silicone impregnated orfluoropolymer infused nickel material, such as nedox, or a nickel-silveralloy, such as nikasil and the like, to reduce friction between theguidewire 42 and the inner coil 92. If desired, a structure similar tothat provided by the inner sheath 40 or the outer sheath 58 may beprovided between the proximal end 32 of the drive shaft 26 and theaperture 44 in the housing 36 to direct the guidewire 42 from theproximal end 32 of the drive shaft 26 to the aperture 44. In addition,the guidewire lock mechanism 50 illustrated in FIGS. 1 through 3 and 10may also be provided, if desired, adjacent the aperture 44 to fix theguidewire 42 with respect to the removal device 176.

The distal end 34 of the drive shaft 26 extends through the aperture 38in the housing 36 and is connected by suitable means, such as solder,braze and the like, to the proximal end of the drive shaft 92. A sealmay be provided adjacent the aperture 38 through which the drive shaft26 sealingly passes to limit fluid flow into the housing 36. Anotherseal may be provided within the drive shaft 26 adjacent the aperture 38through which the guidewire 42 can sealingly pass to further limit fluidflow into the housing 36. While this embodiment 176 is shown in FIG. 12as not including a manifold assembly, it is to be recognized that theembodiment 176 can employ a manifold assembly, such as the manifoldassemblies 22 (FIG. 1) or 144 (FIG. 10). The addition of a manifoldassembly, possibly along with addition of appropriate lumens and otherstructures in the catheter assembly 178, can enable the removal device176 capable of providing irrigation, drug delivery, aspiration, etc. Theremoval device 176 can also include the dilation member 158.

The housing 36 includes a shoulder member 180 extending from the housing36 and surrounding the aperture 38 and the portion of the drive shaft 26extending distally of the aperture 38. The shoulder member 180 may besubstantially cylindrical in shape. A portion of the outer surface ofthe shoulder member 180 includes threads or grooves 182, thesignificance of which will be discussed later, which extendsubstantially diametrically inward on the outer surface of the shouldermember 180. The grooves 182 are part of a removal element expansioncontrol mechanism 184 for positively moving the removal element 16,located at a distal end of the drive shaft 92, between the contractedand expanded positions.

In an exemplary embodiment, the inner coil 94 may be a tri-filar coil of0.005" diameter 304 stainless steel wire. The inner coil 94 may have aninner diameter of about 0.0165" and an outer diameter of about 0.0265".These dimensions allow the removal device 176 to be delivered over aguidewire 42 having a diameter of about 0.010" to 0.014". The choice ofguidewire 42 outer diameter may depend upon utilization of aspiration.The axial length of the inner coil 94 may be about 140 cm, but otherlengths are possible if desired. The inner coil 94 may be provided withvarious pre-load options, e.g. to reduce torsional flexibility andincrease torsional rigidity of portions of the drive shaft 92, by knownmethods. The pre-load options of the inner coil 92 are chosen such thatthe inner coil 94 can efficiently deliver torque to the removal element16 while also being able to navigate through a vascular lumen over aguidewire 42 and to effectively move the removal element 16 between thecontracted and expanded positions. For instance, by pre-loading oraxially twisting a wire during formation of a portion of the coil 92,that twisted portion can have increased rigidity as compared to anotherportion of the coil 92. The portion having increased rigidity canfacilitate pushability of the removal device 176 while the other portionof the coil 92, having less rigidity, can facilitate trackability of thedevice 176.

The coating 100 may be provided, e.g. in the form of a 0.002" thick heatshrink fluoropolymer tube which is applied to the outer diameter surfaceof the drive shaft 92 along its entire axial length. However, thecoating 100 may not cover the distal end 98 of the inner coil 94, thesignificance of which will become clear later. The length of the coating100 may be chosen to determine the location of an irrigation port on adistal portion of the drive shaft 92. In an exemplary embodiment, thebraid 96 may be formed from eight 0.002" diameter 304 stainless steelwires braided at about 40 pics per inch. The braid 96 may be about 100cm long, and is tensioned and attached to the outer diameter surface ofthe inner coil 94 as discussed earlier. Because the braid 96 may not beas long as the inner coil 94, the outer diameter or profile of the driveshaft 92 reduces distally of a distal end 186 of the braid 96. Thus, theprofile of the portions of the catheter assembly 178 distal of thedistal end 186 can also be correspondingly reduced. This reduced profilecan increase the accessibility of some vascular occlusions to theremoval device 176.

The catheter assembly 178 includes a catheter shaft 188 which surroundsthe length of the drive shaft 92 substantially from the distal end 34 ofthe drive shaft 26 to the proximal end of the removal element 16. In anexemplary embodiment, the catheter shaft 188 may be a 0.002" thick tubeof a suitable polymeric material, such as KYNAR and the like, and may beabout 135 cm long. The catheter shaft 188 may be provided in otherlengths. For example, the proximal portion of the catheter shaft 188,measuring about 100 cm, may have an outer diameter of about 1.3 mm,while a distal portion thereof, measuring about 35 cm, may have an outerdiameter of approximately 1 mm. The juncture between the proximal anddistal portions of the catheter shaft 188 is adjacent the distal end 186of the braid 96 or the outer coil of the drive shaft 92.

A proximal end 190 of the catheter shaft 188 is attached to an innerdiameter surface of a strain relief tube 192 by a suitable adhesive,such as a cyanoacrylate, urethane or similar adhesive. The strain relieftube 192 may be substantially cylindrical and may have a thickness ofabout 0.003" and an axial length of about 4 cm. The strain relief tube192 may be made from a suitable polymeric material, such as anylon-polyether blend like PEBAX (France) and the like. The strainrelief tube 192 is of suitable construction for absorbing strains on thecatheter assembly 178.

The outer diameter surface of the strain relief tube 192 is attached toan adjustment member 194 by a suitable adhesive, such as acyanoacrylate, a urethane, or the like. The adjustment member 194 may bemade from a suitable polymeric material, such as polycarbonate,polyurethane and the like, and may be substantially cylindrical inconfiguration. The adjustment member 194 has an inner diametersufficient so that the adjustment member 194 can surround the driveshaft 92, the shoulder portion 180, the catheter shaft 188 and thestrain relief tube 192. A suitable seal may be disposed between theouter surface of the shoulder portion 180 and the inner surface of theadjustment member 194 to limit fluid from flowing between the shoulderportion 180 and the adjustment member 194.

The adjustment member 194 cooperates with the shoulder portion 180 toform the expansion control mechanism 184 for positively moving theremoval element 16 between the contracted position of FIG. 13 and theexpanded position of FIG. 14. Specifically, at least one tab 196 extendssubstantially diametrically inward from the inner surface of theadjustment member 194 towards the outer surface of the shoulder portion180. The tab 196 has a configuration complementary to the configurationof the grooves 182 on the outer surface of the shoulder portion 180 sothat the tab 196 can be inserted into and mate with the grooves 182. Thetab 196 can be shifted out of one groove 182 and into an adjacent groove182 by application of a suitable force to the adjustment member 194. Tofacilitate shifting of the tab 196 between adjacent grooves 182, theadjustment member 194 has an actuating portion 198 having aconfiguration adapted for accepting force manually applied by a treatingphysician.

By applying an appropriate force to the actuating portion 198, thephysician can move the tab 196 between adjacent grooves 182 on theshoulder portion 180. The adjustment member 194 moves in unison with thetab 196, which also causes corresponding movement of the strain relieftube 192 and the catheter shaft 188. Because the tab 196 and theadjustment member 194 move axially with respect to the grooves 182 andthe shoulder portion 180 responsive to application of forces by thetreating physician to the actuating portion 198, the catheter shaft 188conjointly moves axially with respect to the drive shaft 92. Relativeaxial movement of the drive shaft 92 and the catheter shaft 188 causescorresponding movement of the removal element 16 between the contractedposition of FIG. 13 and the expanded position of FIG. 14. If the grooves182 are thread-like, relative axial movement of the drive shaft 92 andthe catheter shaft 188 may be accomplished by rotation of the adjustmentmember 194 about the shoulder portion 180. Scaling means 200 is alsoprovided on the expansion control mechanism 184 for giving the treatingphysician a visual indication of the position of the removal element 16.The position of the removal element 16 may also be verifiable byradioscopic visualization techniques. It is to be noted that, in somealternative embodiments of the removal device 176, the expansion controlmechanism 184 may be constructed so that catheter shaft 188 may beselectively detached from the drive assembly 12.

The construction of the distal end of the removal device 176 is moreclearly illustrated in FIGS. 13 and 14. The inner coil 94 of the driveshaft 92 extends through the entire axial length of the removal element16. The distal end 98 of the inner coil 94 is attached to the distalannulus 106 within the aperture 110 by suitable means, such as braze,solder or the like, as discussed earlier with respect to attachment ofthe wires 102 to the annuluses 104 and 106. In this embodiment 176,however, it is to be recognized that the guidewire 42 does not have abearing surface 112 and that the aperture 110 in the distal annulus 106may be of sufficient size to allow withdrawal of the guidewire 42therethrough. This is a distinction over the previously-discussedembodiments of the invention and is possible because the guidewire 42 isnot used to move the removal element 16 between the collapsed positionand the expanded position. However, in some circumstances, it may bedesirable to have a guidewire 42 which cannot be withdrawn from theremoval device 176 during operation thereof, such as when it isdesirable to retain the removal element 16 on the guidewire 42. Withthis embodiment 176, it may not be necessary to have a non-occludedlumen within the vasculature of sufficient size to accept the coil 114or distal portions of the guidewire 42 in order to remove occlusionmaterial with the removal device 176.

Proximal ends 202 of the wires 102 are attached to an annular expansionbearing surface or member 204 by suitable means, such as a weld, braze,solder or the like. In an exemplary embodiment, the proximal ends 202are brazed to the bearing member 204 with a Turbo braze paste availablefrom Turbo Braze Corporation of Union, N.J. The bearing member 204cooperates with a complementary bearing surface or member 206 attachedto a distal end 208 of the catheter shaft 188 by a suitable adhesive,such as a cyanoacrylate, urethane, or other adhesive. In an exemplaryembodiment, the bearing members 204 and 206 may comprise 21XX hypotubesformed from 304 stainless steel and available from Micro Group, Inc. ofMedway, Mass.

The bearing members 204 and 206 have complementary configurations suchthat one member 204 or 206 can freely rotate within the other member 204or 206. For instance, the bearing members 204 and 206 may be flared andnecked-down, respectively, to facilitate relative rotation of themembers 204 and 206. In the illustrated embodiment, the bearing member204 has a relatively large outer diameter portion 210 and a relativelysmall outer diameter portion 212 with the portion 210 being locateddistally of the portion 212. The wires 102 are attached to the outersurface of the portion 210 and the bearing member 204 has a constantinner diameter to accept the inner coil 94. In some embodiments of theremoval device 176, the bearing member 204 may be substantiallycylindrical in configuration having constant inner and outer diameters.The bearing member 206 has a relatively large inner diameter portion 214and a relatively small outer diameter portion 216 with the portion 214being located distally of the portion 216. The outer diameter of theportion 216 is substantially equal to the inner diameter of the distalend 208 of the catheter shaft 188 to insure a firm connection betweenthe catheter shaft 188 and the bearing member 206. The inner diameter ofthe portion 214 of the bearing member 206 is slightly larger than theouter diameter of the portion 212 of the bearing member 204. Thus, theportion 212 of the bearing member 204 is insertable into the portion 214of the bearing member 206. Accordingly, when the motor 24 is energized,the bearing member 204 can rotate within the bearing member 206. In someembodiments of the device 176, a lubricous or low friction substance217, such as a fluoropolymer, nedox and the like, may be coated onto theouter surface of the portion 212 and the inner surface of the portion214, as well as other mating surfaces, to facilitate rotation of thebearing member 204 within the bearing member 206. It is to beappreciated that, in other embodiments, the bearing member 206 mayrotate within the bearing member 204. Any construction of the bearingmembers 204 and 206 is possible as long as the proximal end of theremoval element 16 is capable of free-wheeling movement with respect tothe catheter shaft 188.

Further structural details of the embodiment 176 may become more clearwith reference to the following discussion of the operation thereof.Again, it is to be noted that the elements of each of the embodiments10, 142 and 176 of the invention may be combined in any suitable fashionto produce a vascular occlusion material removal device having desiredproperties. For instance, it is to be recognized that any of theembodiments of the material removal element expansion limiting means maybe included with the removal device 176. The removal device 176functions substantially similarly to the removal devices 10 and 142disclosed earlier except for the method of moving the removal element 16between the contracted and expanded positions. Thus, the discussion ofoperation of the removal device 176 will be limited to the method ofexpanding the removal element 16.

It is to be noted that, in the contracted position, the adjustmentmember 194 is positioned closest to the drive assembly 12. With theremoval element 16 in the contracted position of FIG. 13, a treatingphysician wishing to move the removal element 16 towards the expandedposition (FIG. 14) applies a suitable force to the actuation portion 198of the adjustment member 194. This force removes the tab 196 from theproximal-most groove 182 and shifts the tab 196, along with theadjustment member 194, distally along the shoulder portion 180. As theadjustment member 194 moves distally along the shoulder portion 180, thestrain relief tube 192 and the catheter shaft 188 also conjointly moveaxially with respect to the drive shaft 92 in the distal direction.

Because the distal end 98 of the drive shaft 92 is fixed to the distalannulus 108 and the removal element 16, distal axial movement of thecatheter shaft 188 with respect to the drive shaft 92 reduces the axialdistance between the distal annulus 108 and the bearing members 204 and206. The bearing member 206 transmits force from the catheter shaft 188to the bearing member 204, and, from there, to the wires 102. Oppositeends of the braided wires 102 are attached to the distal annulus 108 andthe bearing member 204, respectively, such that reduction of the axialdistance between the distal annulus 108 and the bearing member 204causes the wires 102 to bow radially outwardly from the inner coil 94 ofthe drive shaft 92.

In this manner, the removal element 16 moves between the contractedposition of FIG. 13 and the expanded position of FIG. 14. Because theremoval element 16 moves between the contracted and expanded positionsresponsive to movement of the catheter shaft 188, the scaling means 200provides the treating physician with a visual indication of the diameterdefined by the wires 102. It is to be noted that this removal element 16expanding movement of the catheter shaft 188 can also be viewed, from asuitable reference frame, as the drive shaft 92 shifting with respect tothe removal element 16. Therefore, it is equally valid to refer toexpansion of the removal element 16 responsive to movement of the driveshaft 92 or the catheter shaft 188 with respect to the removal element16.

Once the desired positioning of the removal element 16 is achieved, thetreating physician releases the actuation portion 198, and the tab 196comes to rest in a groove 182. This locks the removal element 16 in thedesired position. If it is desired to move the removal element 16 backtowards the contracted position, the above-discussed steps are repeated,but the direction of the force applied to the actuating portion 198 ofthe adjustment member 194 is reversed to cause movement of theadjustment member 194 and the catheter shaft 188 proximally towards thedrive assembly 12.

Yet still a further embodiment 218 of the invention is illustrated inFIG. 17. The embodiment 218 is substantially similar to the embodiment176 except for the differences noted below, hence the like referencenumerals for similar structures. The embodiment 218 differs from theembodiment 176 in that the removal element 16 includes a collectionportion 220 for collecting occlusion particulate 222 removed from avascular occlusion 224. The collection portion 220 may be provided withthe removal devices 10 and 142 as well. Also, it is to be recognizedthat, while the collection portion 220 is illustrated in FIG. 17 asbeing disposed on a distal end of the removal element 16, the collectionportion 220 may alternatively be disposed on the proximal end of theremoval element 16. Generally, the collection portion 220 is located onthe removal element 16 at a position where particulate 222 from theocclusion 224 may be collected, and thus, the disposition of thecollection portion 220 may depend upon whether the removal element 16 isto be moved proximally or distally against the occlusion 224.

In the illustrated embodiment of the removal device 218, the collectionportion 220 is disposed on a distal portion of the removal element 16 sothat particulate 222 removed from the occlusion 224 will naturally movetowards the collection portion 220 under the influence of fluid flowthrough the vasculature. Movement of particulate 222 into the collectionportion 220 can further be insured by utilizing the removal device 218to remove occlusion material while being moved proximally across theocclusion 224, viz. in a direction opposite to the direction of fluidflow through the lumen. This method of operation of the removal device218 will be discussed in greater detail later. In an alternativeembodiment of the removal device 218, fluid may be provided through thedrive shaft 92 and/or the catheter shaft 188 so that this fluid flow candirect particulate 222 into the collection portion 220. The fluid may befiltered by a retention member or coating 226 forming the collectionportion 220 and may be able to exit the collection portion 220 throughthe aperture 110 in the annulus 106. Because the collection portion 220is disposed on the distal portion of the removal element 16, it may notbe desirable to place abrasive 105 on the portions of the wires 102forming the collection portion 220.

In an exemplary embodiment of the removal device 218, the collectionportion 220 may be formed by a retention member in the form of apolymeric coating 226, such as polyurethane, Pellathane™ (Dow Chemical)and the like, disposed on the distal portion of the removal element 16.The polymeric coating 226 may be applied to the wires 102 in a number ofways, such as by dipping the removal element 16 in the polymer, sprayingthe polymer onto the wires 102 with, for example, an air brush, directlyapplying the polymer to the wires 102, etc. The coating 226 is appliedto the wires 102 such that at least the outer surfaces of the wires 102are coated, and so that, when the removal element 16 is moved into theexpanded position, the coating 226 will stretch across and cover spacesbetween adjacent wires 102. In this manner, the coating 226 forms aboundary of a particulate collection chamber 228 located at the interiorof the removal element 16. It is to be noted that, in some embodimentsof the removal device 218, the collection portion 220 may not be formedfrom a polymeric coating 226, but may be formed from a fabric orfilter-like material, such as GORTEX and the like, or a polypropylenescreening material. In general, the collection portion 220 is formedfrom any suitable material having apertures whose diameters measureabout 5 microns. These apertures may allow blood or other fluid to passdistally through the collection portion 220 while retaining occlusionparticulate 222 larger than 5 microns within the collection portion 220.In some embodiments, the collection portion 220 may be able to occludefluid flow. These embodiments of the collection portion 220 mayfacilitate removal of occlusion particulate by aspiration because fluidwould not flow beyond the collection portion 220. Thus, the scope of theclaims is not to be limited by the above-discussed constructions of thecollection portion 220.

The various embodiments 10, 142, 176 and 218 of the present inventionalso provide a number of methods for performing intravasculartreatments, such as removing or displacing vascular occlusion material.These methods comprise a plurality of steps, some of which have beendiscussed in detail already, so the following discussion of the methodswill simply refer back to those detailed discussions, instead ofrestating them, where appropriate. As with the mechanical elements ofthe embodiments 10, 142, 176 and 218 of the invention, the steps of themethods may also be combined in suitable fashion to perform a desiredtreatment.

The expandable intravascular occlusion material removal device 10, 142,176 or 218 is inserted into the patient's vascular system through asuitable puncture or other access site, such as via the femoral artery,in well known fashion. At this point, the expandable material removalelement 16 is in the radially contracted position shown in FIG. 4.Because the removal device 10, 142, 176 or 218 has a low profile whenthe material removal element 16 is in the contracted position, theintravascular portion of the removal device 10, 142, 176 or 218 can beinserted through a conventional 7 French guide catheter, well known tothose having ordinary skill in the relevant art. The removal device 10,142, 176 or 218 is moved over the medical guidewire 42, which has beenpreviously positioned in proximity to the intravascular treatment site,until the distal end of the annulus 106 is adjacent the proximal end ofthe bearing surface 112, if present, as discussed hereinabove. Now, theexpandable material removal element 16, currently in the contractedposition, is located in close proximity to the vascular occlusionmaterial to be removed thereby.

At any time, a fluid, such as saline, a drug therapy, heparinizedsaline, an oxygenated fluid, such as FLUORSOL, and the like, can beapplied to the port 80 on the manifold assembly 22 or 144 from asuitable fluid source. The fluid flows through the port 80 and into theportion of the main lumen 78 located between the fluid seal 84 and 86,and from there, through the aperture 88 into the hollow interior of thedrive shaft 92. The fluid flows along the axial length of the driveshaft 92 and passes into the hollow interior defined by the braidedwires 102 of the expandable material removal element 16. The fluid canflow through spaces between adjacent portions of the braided wires 102to infuse the intravascular treatment site with fluid. Alternatively,with the embodiment 176, the fluid may flow through the aperture 110 inthe distal annulus 106. Also, the location at which the fluid exits thedrive shaft 92 may be predetermined by appropriately choosing the lengthof the coating 100. This may provide for maintenance of fluid within avascular lumen if aspiration is used.

At any time, another fluid to be infused into the patient, or a negativepressure to aspirate the intravascular treatment site may be applied tothe port 82 from a suitable source. The fluid or the negative pressureis applied through the port 82 to the hollow interior of the cathetersheath 90, 152 or 188 and from there to the vascular lumen adjacent thedistal end 18, 160 or 208 of the catheter assembly 14, 146 or 178,respectively. Because of the relative locations of the distal ends ofthe drive shaft 92 and the catheter sheath 90, 152 or 188, as discussedearlier, effective aspiration of the treatment site may be provided.This is important because some vascular occlusion material, such ascertain types of thrombus, may be removed from a vascular surface oranother occlusion simply by aspiration.

In some other embodiments of the removal device 10, 142, 176 and 218,aspiration may be provided by an impeller-like element operativelyattached to the drive shaft 92 such that rotation of the drive shaft 92and the impeller element generates a fluid flow within the vascularlumen, thereby causing particulate 222 to flow into the catheter sheath90, 158 or 188. In other embodiments, multiple impeller-like elementsmay be attached to the shaft 92 at various locations along thelongitudinal axis thereof.

If desired, the removal devices 10, 142, 176 or 218 may be deliveredthrough another catheter, such as the guide catheter discussed earlier.If this is done, fluid may be provided through the drive shaft 92 and/orthrough the catheter sheath 90, 152 or 188. This fluid may generate apositive pressure within the vascular lumen. At the same time, anegative pressure may be provided through the guide catheter. This couldproduce a pressure differential within the vascular lumen which couldforce fluid and occlusion particulate 222 proximally through the guidecatheter and out of the patient's body. This method may also be used toforce fluid and occlusion particulate 222 proximally through thecatheter sheath 90, 158 or 188. In still other embodiments, a dilationmember may be provided at the distal end of the guide catheter, and/oranother dilation member, similar to an angioplasty balloon may belocated distally of the removal element 16. By intravascularly inflatingboth of these dilation members, the intravascular treatment site may besubstantially isolated, which can facilitate particulate 222 removal.

With the expandable material removal element 16 being positioned withrespect to the vascular occlusion material to be removed, treatingphysician can expand the material removal element 16 to the desireddegree by implementing the methods discussed earlier with respect to theguidewire lock mechanism 50 and the material removal element expansioncontrol mechanism 52 for the embodiments 10 and 142, and with respect tothe expansion control mechanism 184 for the embodiments 176 and 218. Thematerial removal element 16 can be moved into a plurality of positionsby variably expanding and/or contracting the material removal element16. Thus, multiple material removal element 16 sizes, shapes, profilesand characteristics may be achieved with the use of a single occlusionmaterial removal device 10, 142, 176 or 218. The controlled, incrementalexpansion and contraction of the expandable material removal element 16can provide a treating physician with greater flexibility in performingintravascular treatments, as well as possibly reducing the costs of suchtreatments because multiple pieces of equipment need not be used. Thisis a significant improvement over some of the intravascular treatmentdevices of the prior art. In addition, the various constructions of thematerial removal element radial expansion limiting means may insure thatthe material removal element 16 is not over-expanded.

With the removal device 142, either before of after expansion of theexpandable material removal element 16, the dilating member 158 can beinflated to a suitable pressure by application of a pressurized fluid tothe port 148, as discussed above. The pressurized fluid flows throughthe port 148 and the lumen 156, and into the interior of the dilatingmember 158. The dilating member 158 expands sufficiently so that anouter surface thereof engages the interior surface of the vascularlumen. The dilating member 158 can be inflated to pressures on the orderof 4 to 8 atmospheres and can center and stabilize distally-locatedportions of the removal device 142 during operation thereof. Inflationof the dilating member 158 can also be used to occlude blood flowthrough the vasculature being treated.

The removal device 10, 142, 176 or 218 is now ready to remove vascularocclusion material from a vascular surface or from a vascular occlusionby expansion and/or rotation of the expandable material removal element16. It is to be noted that, because the expandable material removalelement 16 is comprised of braided wires 102 which define spaces betweenadjacent wires 102, expansion of the material removal element 16 may notocclude fluid flow through the vascular lumen. For example, fluidsinfused into the vasculature by the device 142 at a location distally ofthe dilating member 158 can flow around and through the spaces betweenthe braided wires 102 and continue through the patient's vasculaturedistally of the material removal element 16.

If the occlusion material were located radially above the materialremoval element 16, then appropriate expansion of the wires 102 canallow the abrasive 105 or other cutting surface on the wires 102 to biteinto a portion of the occlusion material. This radial cutting of thewires 102 into the vascular occlusion material can cause a portion ofthe material to pass through spaces between adjacent wires 102 and becaptured in the hollow interior of the material removal element 16defined by the wires 102. The expansion of the braided wires 102 definesa radially directed cutting vector for severing occlusion material. Theeffectiveness of this radial cutting may depend upon the composition orhardness of the vascular occlusion material. If desired, the expandablematerial removal element 16 can be moved into the contracted position,thereby trapping occlusion material within the hollow interior definedby the braided wires 102. The material removal element 16 can be removedfrom the patient's vasculature if desired and the occlusion materialwill be retained within the hollow interior of the material removalelement 16 because of the spring-like forces inherent in the wires 102.With the removal device 218, retention of occlusion material within thecollection chamber 228 within the hollow interior of the braided wires102 is enhanced by the coating 226. The captured material can be laterretrieved for performing a biopsy or other procedure on the material.

Some occlusion material may not be susceptible to removal in thisfashion. For instance, some occlusion material may be relatively hard orcalcified, thereby making it rather difficult for the wires 102 to biteinto the material upon expansion of the material removal element 16. Ifthis is the case, then the material removal element 16 can be expandedsuch that the outer surfaces of the braided wires 102 contact theinterior surface defined by the occlusion. In other words, the materialremoval element 16 is expanded to define a cutting diameter slightlylarger than a non-occluded diameter of a particular portion of thevasculature. By expanding the diameter of the removal element 16 to asize slightly larger than the non-occluded diameter of the vascularlumen, more effective and more efficient removal of occlusive materialis provided as compared to some prior art methods where a cuttingelement is expanded to define a diameter equal to that of the vascularlumen. The material removal element 16 is expanded and is locked in thisexpanded position according to the methods described earlier withrespect to the guidewire lock mechanism 50 and the material removalelement expansion control mechanism 52 for the embodiments 10 and 142,and with respect to the expansion control mechanism 184 for theembodiments 176 and 218. The maximum radial expansion of the materialremoval element 16 is limited by the radial expansion limiting meansdiscussed hereinabove.

Once locked in the expanded position, the treating physician actuatesthe control switch 30, thereby energizing the motor 24. The motor 24induces rotation of the drive shaft 26, which, in turn, causes the driveshaft 92 to rotate within the catheter sheath 90, 152 or 188. Thematerial removal element 16 is also rotated conjointly with the driveshafts 26 and 92. The rotation of the material removal element 16enables the sharp edges or abrasive 105 particles on the surfaces of thebraided wires 102 to cut, abrade, ablate, or otherwise remove vascularocclusion material from a vascular lumen surface or a vascularocclusion.

Rotation of the braided wires 102 defines a cutting vector directedtangentially to the surface interface between a given wire 102 and theocclusion material. The removed occlusion material can pass through thespaces between adjacent wires 102 and be caught in the collectionchamber 228 or the hollow interior defined by the braided wires 102comprising the material removal element 16. This removed material can betrapped within the material removal element 16 upon contraction thereof,as described earlier, and subsequently removed from the patient'svasculature along with the material removal element 16. With theembodiment 218, the coating 226 can facilitate retention of particulate222 within the chamber 228. Alternatively, the removed vascularocclusion material can be drawn into the interior of the catheter sheath90 or 152 by means of negative pressure applied to the port 148. Thus,there are at least three ways by which removed vascular occlusionmaterial can be carried away from the patient's vasculature.

After a sufficient amount of vascular occlusion material has beenremoved by rotation of the material removal element 16, the non-occludeddiameter of the vascular lumen is enlarged, but further occlusivematerial may remain within the vascular lumen. It may be desirable toremove more occlusion material, thereby further enlarging thenon-occluded diameter of the vascular lumen. To do this, the expandablematerial removal element 16 is further radially expanded, according tothe steps of the method discussed earlier, to define a cutting diameterslightly larger than this second, non-occluded diameter of the vascularlumen. This process of expanding the cutting diameter of the materialremoval element 16 progressively--starting small and finishinglarge--can be repeated as often as necessary until a non-occludeddiameter of the desired length is formed in the vascular lumen. Thisprogressive cutting process allows for more efficient removal of theoccluding material by always using a cutting diameter just slightlylarger than the non-occluded diameter. The expandable nature of thematerial removal element 16 allows this process to be executed whileutilizing only one intravascular device 10, 142, 176 or 218. Also, thisprocess can be used in conjunction with moving the device 10, 142, 176or 218 either distally or proximally against the occlusion.

It is possible that a particular vascular lumen might have more than oneocclusion which may be located distally of a first occlusion. If this isthe case, after sufficient material of the first occlusion is removed torevascularize that portion of the lumen, then the material removalelement 16 can be repositioned intravascularly adjacent a secondocclusion for removing its occluding material. To reposition thematerial removal element 16, the dilating member 158, if inflated,should be deflated. The material removal element 16 should also be movedinto the contracted position. The material removal element 16, thedilating member 158 and the distal portion of the catheter assembly 14,146 and 178 assume a low profile for facilitating intravascular movementof the removal device 10, 142, 176 or 218. The entire removal device 10,142, 176 or 218 can now be freely repositioned for removing materialfrom the second occlusion. It is envisioned that, in some embodiments ofthe invention, the drive shaft 92 and the cutting element 16 may beaxially shiftable with respect to the catheter sheath 90, therebyfacilitating intravascular repositioning of the removal element 16.

Once properly positioned adjacent the second occlusion, the materialremoval element 16 can be expanded as before and the same process ofocclusion material removal can be performed. There may be someocclusions, however, which define a non-occluded diameter smaller thanthe outer diameter defined by the braided wires 102 in the contractedposition. With the removal devices 176 and 218, the guidewire 42 may bewithdrawn sufficiently such that the cutting surface 108 on the distalannulus 106 can engage and remove occlusion material. However, if thenon-occluded diameter were large enough to accept the coil 114 of theguidewire 42 and the bearing surface 112, if present, then the occlusionmaterial can still be removed by the material removal element 16. Inthis case, the coil 114 of the guidewire 42 and the bearing surface 112,if present, are passed through the non-occluded diameter sufficiently tobring the cutting surface 108 on the distal annulus 106 into contactwith a proximal end of the occlusion. The cutting is surface 108 has aconfiguration or an abrasive 105 coating which facilitates removal ofvascular occlusion material upon rotation of the distal annulus 106. Inaddition, as the Figures show, the cutting surface 108 is tapered sothat a relatively smaller cutting diameter encounters the occlusionmaterial initially.

The motor 24 is energized, thereby rotating the material removal element16 and the distal annulus 106, and the cutting surface 108 begins tobore through the occlusion material. The cutting action of the cuttingsurface 108 is directed substantially longitudinally or axially withinthe vascular lumen, and the cutting surface 108 can grind away occlusionmaterial from the occlusion or the vascular surface, thereby increasingthe size of the non-occluded diameter in the vascular lumen. Of course,aspiration can be used to carry the removed material away from thepatient. The treating physician can apply an axially directed force tothe removal device 10, 142, 176 or 218 as the cutting surface 108rotates to move the cutting surface 108 distally through the occlusion.Since the cutting surface 108 is tapered, a progressively larger cuttingdiameter is engaged against the vascular occlusion as the cuttingsurface 108 and the associated removal device 10, 142, 176 or 218 aremoved distally within the vascular lumen. Thus, the cutting surface 108also executes substantially the same occlusion material removal processdescribed above by starting with a small cutting diameter and graduallyincreasing that diameter as progressively more occluding material isremoved.

The cutting surface 108 is rotated against the occlusion andsimultaneously advanced distally with respect to the occlusion to forman enlarged diameter pilot hole longitudinally through the occlusion.This process is illustrated in FIG. 15 with respect to the removaldevice 176. As more proximal portions of the cutting surface 108encounter the occlusion material, the cutting surface 108 may cutocclusion material along vectors directed tangentially to the interfaceof the cutting surface 108 and the occlusion. It is to be noted that aproximal-most portion of the cutting surface 108 defines an outerdiameter substantially equal to the outer diameter defined by thebraided wires 102 when in the contracted position, as shown in FIG. 15.Thus, the pilot hole formed by the cutting surface 108 has dimensionssufficient for accepting the material removal element 16 in thecontracted position. Therefore, once this pilot hole has been formed,the motor 24 can be stopped, which ceases rotation of the materialremoval element 16 and the cutting surface 108. The expandable materialremoval element 16 can be positioned within the pilot hole and thedilating member 158, if provided, can be expanded to provide addedstability to the distally-located portions of the device 142 or toocclude blood flow through the vascular lumen. At this point, theexpandable material removal element 16 can be expanded, according to theabove-discussed processes, within the pilot hole so that the braidedwires 102 engage the occlusion material. This method is substantiallysimilar to that illustrated in FIG. 16 with respect to the embodiments176. The spring-like properties of the wires 102 can allow the removalelement 16 to conform to the configuration of the occlusion whenexpanded, as will be discussed in greater detail later. The motor 24 canagain be energized, and the rotating material removal element 16 canremove additional occluding material. The removal elements 16 may beexpanded while the motor 24 is running.

In any case, once sufficient occlusion material has been removed, it maybe desirable to perform balloon angioplasty within the vascular lumen inorder to displace any remnants of the occlusion. To perform bothocclusion material removal and angioplastic displacement of an occlusionremnant, the removal device 142 is used. After the motor 24 and therotation of the expandable material removal element 16 has been stopped,the material removal element 16 is moved into the contracted position sothat the braided wires 102 of the removal device 142 define a lowprofile. If the dilating member 158 was expanded during operation of thematerial removal element 16, then it too should be deflated, byreversing the above-discussed pressure flow, so that the entire distalportion of the removal device 142 defines a low profile for facilitatingintravascular movement of the removal device 142.

The catheter assembly 146 of the removal device 142 is shifted distallywithin the vascular lumen to locate the contracted dilating member 158adjacent the remnants of the occlusion. The treating physician may havean easier time of properly positioning the dilating member 158 withrespect to the occlusion remnants because the marker band 164 rendersthe position of the dilating member 158 radioscopically visible. Onceproper position has been attained, the dilating member 158 can beinflated, as discussed above, to a sufficient pressure, typically on theorder of 4 to 8 atmospheres, to displace the remnants and furtherrevascularize the vascular lumen.

A further method of removing occlusion material begins with locating theremoval element 16, in the contracted position, distally of theocclusion material. The removal element 16 is expanded, as describedabove, and is then shifted proximally in the lumen toward he occlusion.The removal element 16 may be energized such that the rotating removalelement 16 removes occlusion material from a distal end of the occlusionupon contact with the occlusion. The removal element 16 can be movedproximally progressively until sufficient occlusion material has beenremoved to revascularize the lumen.

A variation of this method is illustrated in FIG. 17 with respect to theremoval device 218. FIG. 17 shows the removal element 16 locateddistally of the occlusion 224. This location of the removal element 16may be achieved if the non-occluded lumen through the occlusion 224 issufficient to accept the removal element 16 in the contracted position,or by forming a pilot hole through the occlusion 224 as discussedhereinabove. The removal element 16 is moved towards the expandedposition by operation of the expansion control mechanism 184 to deploythe wires 102 to remove occlusion material and to deploy the collectionportion 220 to capture particulate 222.

Once expanded, the removal element 16 is energized and the element 16and the removal device 218 are moved proximally against the occlusion224. The wires 102 remove particulate 222 from a distal portion of theocclusion 224. Because the collection portion 220 is located distally ofthe abrasive-coated wires 102 and the occlusion 224, particulate 222removed from the occlusion 224 moves towards the collection portion 220under the influence of fluid flowing through the vascular lumen. Asnoted earlier, fluid may be supplied through the catheter shaft 188 todo this, although blood flow through the lumen may be sufficient.

As the particulate 222 is removed from the occlusion 224, theparticulate 222 moves into the interior of the removal element 16through the spaces between adjacent abrasive-coated wires 102 and intothe collection chamber 228 defined by the retention member or coating226. The coating 226 retains the particulate 222 within the collectionchamber 228 while allowing fluid to flow therethrough. The energizedremoval element 16 is progressively moved proximally against theocclusion 224. The location of occlusion material removal, defined bycontact between the abrasive-coated wires 102 and the occlusion 224, isalways proximal of the location of particulate 222 collection, definedby the coating 226. Some, if not all, of the particulate 222 removedfrom the occlusion 224 should be collected within the collection portion220. Thus, the collection portion 220 may reduce the amount ofparticulate 222 that floats away from the occlusion 224 and the removaldevice 218. Once sufficient occlusion material is removed, or once thecollection portion 220 is filled with particulate 222, the removalelement 16 can be moved towards the contracted position and removed fromthe patient. The coating 226 may insure that particulate 222 is retainedwithin the collection portion 220.

According to another method for removing vascular occlusion material,the removal element 16 can be inserted into a vascular lumen andpositioned proximally of an vascular occlusion. The removal element 16can then be expanded, by use of the above-discussed methods, to acertain diameter, such as the diameter of a non-occluded portion of thelumen, and advanced within the lumen towards the occlusion. The removalelement 16 is forced into contact with the occlusion, and the wires 102forming the expanded element 16 bite into the occlusion material. Theremoval element 16 is then retracted from the occlusion and readied foranother advance towards the occlusion. At any point, the removal element16 can be collapsed and retracted, as may be desirable to determine thecomposition of the occlusion material, or may be contracted or furtherexpanded, such as discussed above, to define different cuttingdiameters. The steps of this method can be repeated as often as desired.

Still a further method takes advantage of a property provided by theremoval element 16, viz. the removal element 16 can absorb forcesapplied to it and correspondingly deform or deflect. This method alsotakes advantage of the ability of the drive shaft 92 to axially expandor contract during operation. These property may be more readilyunderstood with reference to FIGS. 11 and 16. FIG. 11 illustrates across section of a vascular lumen 166 occluded by occluding material168. The occluding material 168 defines an eccentric surface 170 offsetfrom the vascular lumen 166 by a distance which defines a non-occludeddiameter in the vascular lumen 166. The removal element 16 is insertedinto the non-occluded diameter and expanded, as discussed above, untilan outer surface of the removal element 16 contacts the eccentricsurface 170. Because the removal element 16 can absorb forces applied toit, such as those attendant with expansion or rotation of the removalelement 16, the removal element 16 deflects or deforms such that theremoval element 16 defines a configuration which complements thecorresponding configuration of the eccentric surface 170. Thus, theremoval element 16 can take into account varying occlusion morphology.

Once the removal element 16 has assumed the complementing configuration,as shown in FIG. 16, the motor 24 is activated and the removal element16 begins to rotate within the non-occluded diameter. Deflection of theremoval element 16 formed by the wires 102 causes longitudinal or axialand radial cutting actions or vectors to be reduced correspondingly.This may reduce the probability that healthy tissues might be removedbecause a cushioned, softer engagement may be formed between the healthytissues and the removal element 16 due to the spring-like nature of theremoval element 16. In addition, because the configuration of theremoval element 16 conforms to the configuration of the occlusionmaterial 168, upon rotation of the element 16, a greater concentrationof removing forces can be generated at an area, indicated generally byreference numeral 172, on the occlusion material 168 than the forceconcentration present at an area 174 on the vascular lumen 166.Specifically, cutting forces may be evenly distributed over the area174. This can lead to more efficient removal of vascular occlusionmaterial 168.

Furthermore, it is to be noted that the spring-like nature of theremoval element 16 provides for another method for removing vascularocclusion material. Specifically, according to this method, the removalelement 16 may be placed within a lumen constricted or reduced by anocclusion such that the wires 102 are in proper position with respect tothe occlusion for removal of occlusion material 168. At this point, thewire lock mechanism 50 and the removal element expansion controlmechanism 52 for the removal devices 10 and 142, or the expansioncontrol mechanism 184 for the removal devices 176 and 218 can beactuated, as described hereinabove, in order to expand the removalelement 16 to define a diameter equal to a non-occluded diameter of thesame vascular lumen, i.e. the diameter of the vascular lumen with theocclusion material removed.

The removal element 16 expands to define a configuration whichcorresponds to the configuration of the eccentric surface 170, as shownin FIG. 11 and as similarly depicted in FIG. 16. However, because theocclusion material 168 prevents the removal element 16 from immediatelyexpanding to define the non-occluded diameter, the wires 102 of theelement 16 absorb and store expanding forces in the form of springenergy. This stored spring energy allows the removal element 16 to beessentially self-expanding during operation of the removal device 10,142, 176 or 218.

Specifically, the motor 24 is energized and the removal element 16begins to rotate within the lumen 166, thereby removing vascularocclusion material 168 from the occlusion. As progressively more andmore occlusion material 168 is removed from the occlusion, the springenergy stored within the wires 102 of the element 16 is released whichcauses the removal element 16 to expand further responsive to the amountof occlusion material 168 removed. Stored spring energy may also bereleased if the drive shaft 92 axially expands or contracts duringoperation. The stored spring energy is progressively released as greateramounts of occlusion material 168 are removed until the braided removalelement 16 is expanded to the degree indicated by the removal elementexpansion control mechanism 52 or the expansion control mechanism 184.The removal element expansion limiting means also insures that theremoval element 16 is not over-expanded. The removal element 16 ceasesto expand once sufficient occlusion material 168 has been removed andonce sufficient stored spring energy has been released. At this point,the diameter defined by the expanded removal element 16 should beapproximately equal to the original, non-occluded diameter of thevascular lumen 166.

The self-expanding nature of the removal element 16 provides anothermethod of removing vascular occlusion material from a vascular lumen.According to this method, the removal element 16 is pre-formed orexpanded such that the element 16 defines a certain, pre-determinedconfiguration. By placing the removal element 16 in this configuration,the element 16 is provided with a memory of this shape. Forming theelement 16 with shape memory alloys, such as nitinol and the like, alsoinsures effective shape or configuration memory. The pre-formedconfiguration preferably has dimensions suitable for intravascularinsertion and navigation. The pre-formed removal element 16 ispositioned adjacent the occlusion material, which defines a non-occludeddiameter within the vascular lumen. The removal element 16 is theninserted into the non-occluded lumen.

Contact of the removal element 16 with the occlusion material impartsforces to the braided wires 102 which deform the configuration of theremoval element 16. The spring-like nature of the braided wires 102comprising the removal element 16 allows the element 16 to deform orotherwise comply to a configuration defined by the occlusion material,as illustrated in FIGS. 11 and 16. The element 16 can now be energizedso that occlusion material can be removed. As progressively moreocclusion material is removed, the shape memory of the wires 102 allowsthe element 16 to move towards the initial, pre-determinedconfiguration. Once sufficient occlusion material has been removed, thememory aspects of the removal element 16 allow it to recover from itsdeformed state to its original configuration.

As is evident from the foregoing discussion, the embodiments of thepresent invention provide treating physicians with a number of methodsfor performing intravascular treatments. The individual steps comprisingthese methods can be performed in any order, and steps of one method canbe combined with steps of other methods to achieve desired results. Byproviding an expandable material removal element 16, the embodiments ofthe invention provide a plurality of material removal element 16 sizes,shapes and cutting profiles or characteristics combined in a singleintravascular occlusion material removal device 10, 142, 176 or 218.These shapes, sizes and characteristics are positively variable by thecontrolled incremental expansion of the material removal element 16offered by the guidewire lock mechanism 50 and the material removalelement expansion control mechanism 52 or the expansion controlmechanism 184. Also, the various constructions of the material removalelement radial expansion limiting means prevents over-expansion of thematerial removal element 16. It is to be noted that more efficientremoval of vascular occlusion material may be possible if the motor 24is energized prior to moving the removal element 16 towards the expandedposition because the removal element 16 will gain momentum prior toengagement with the occlusion material.

By combining the material removal element 16 with the cutting surface108, a plurality of differently directed cutting actions can beperformed by the removal devices 10, 142, 176 and 218. Specifically, thematerial removal element 16 is capable of producing cutting actionsdirected radially and tangentially with respect to the vascular lumen orocclusion. In addition, the cutting surface 108 can produce cuttingactions directed tangentially and longitudinally with respect to thevascular lumen or occlusion. Thus, at least three differently directedcutting actions can be produced by the removal devices 10, 142, 176 and218. In addition, the occlusion material can be cut, ground, displaced,captured or aspirated. Specifically, relatively soft occlusion materialcan be sliced or cut by the wires 102 and fall into the hollow interiorof the removal element 16, while relatively hard occlusion material canbe ground by the abrasive 105 on the wires 102. Occlusion material canbe retained within the collection chamber 228 by the coating 226. Thus,a treating physician can have greater flexibility in performingintravascular treatments while using only one device 10, 142, 176 or218.

FIG. 18 is a side view of another embodiment of an expandable vascularocclusion material removal device. The removal device 250 generallycomprises a drive assembly 283, a drive shaft assembly 257, and anexpandable removal element 252 located at a distal end of the driveshaft assembly 257. A proximal end of the drive shaft assembly 257 isconnected to a strain relief 258 which forms a connection between thedrive assembly 283 and the drive shaft assembly 257.

The drive shaft assembly 257 comprises two rotatable coaxial driveshafts including an inner drive shaft 312 and an outer drive shaft 314wherein the inner drive shaft 312 and outer drive shaft 314 may belongitudinally slidable relative to one another and conjointlyrotatable. In addition, the inner drive shaft 312 and the outer driveshaft 314 may move longitudinally together either proximally ordistally. An outer sheath 256 receives the inner drive shaft 312 and theouter drive shaft 314 to prevent the vascular lumen of a patient fromcoming in direct contact with a substantial portion of outer drive shaft314. The inner drive shaft 312 and outer drive shaft 314 may belongitudinally slidable and rotatable with respect to the outer sheath256.

The distal end of the outer drive shaft 314 is operatively coupled tothe proximal end of removal element 252. The distal end of inner driveshaft 312 passes through the removal element 252 and is coupled to thedistal end of removal element 252. By sliding longitudinally the innerdrive shaft 312 and the outer drive shaft 314 relative to one another,the expandable removal element 252 may move between a contractedposition and an expanded position to engage occlusion material within avascular lumen. In addition, by moving the inner drive shaft 312 and theouter drive shaft 314 conjointly in a proximal or distal direction, theremoval element 252 may be moved proximally or distally within thevascular lumen.

Now referring to FIGS. 18-19, the drive assembly 283 provides amechanism for powering and controlling removal device 250 by providingthe following apparatus: (1) a motor 274, turned on and off by powerswitch 278, for conjointly rotating inner drive shaft 312 and outerdrive shaft 314; (2) an actuation control knob 374 for controlling therelative longitudinally shift between the inner drive shaft 312 and theouter drive shaft 314 thereby causing the expandable removal element 252to move between a contracted position and an expanded position to engageocclusion material within the vascular lumen; (3) an elongated slot 390for allowing actuation control knob 374 to be slid proximally ordistally within elongated slot 390 for controlling gross longitudinalconjoint movement of the inner drive shaft 312 and the outer drive shaft314 thereby causing the expandable removal element 252 to movelongitudinally therewith within the vascular lumen; (4) a slide lock 376for locking the longitudinal position of actuation control knob 374within elongated slot 390; (5) a guide wire lock 270 for locking thelongitudinal position of guidewire 288 relative to drive assembly 283;and (6) a solution flush line 284 for providing irrigation to the driveshaft assembly 257 and removal element 252 or for providing infusion offluids, such as contrast media, a saline solution, a drug therapy, orthe like, into the patient.

An exemplary use of the embodiments in FIGS. 18-19 comprises thefollowing steps: (1) navigating a guide catheter (not shown)substantially into the vascular system of a patient; (2) sliding aguidewire 288 into the central cavity of the guide catheter until theguidewire 288 reaches the distal end of the guide catheter; (3)navigating the guidewire 288 from the distal end of the guide catheterfurther into the vascular system of a patient such that the guidewire288 passes distally of the occlusion material to be removed; (4)advancing the removal element 252, drive shaft assembly 257, driveassembly 283, and guide wire lock 270 over the guidewire until theremoval element 252 is adjacent to the occlusion material; (5) lockingthe guidewire into position using guidewire lock 270; (6) looseningslide lock 376 and sliding actuation control knob 374 proximally causingboth the inner drive shaft 312 and the outer drive shaft 314, andtherefore the removal element 252, to move conjointly in the distaldirection thus engaging occlusion material; (7) engaging the controlswitch 278, thereby energizing motor 274 within drive assembly 283 andthus inducing rotation of the inner drive shaft 312 and outer driveshaft 314 which in turn rotates the material removal element 252enabling the sharp edges or abrasive particles on the surfaces ofremoval element 252 to cut, abrade, ablate, or otherwise remove vascularocclusion material from a vascular lumen surface or a vascularocclusion; (8) turning the actuation control knob 374 to move the innerdrive shaft 312 and outer drive shaft 314 relative to one another thuscausing the removal element 252 to expand and engage the occlusionmaterial; (9) advancing removal element 252 into the occlusion materialat a given expanded position until the distal end of the occlusionmaterial is reached; (10) returning removal element 252 proximally untilthe distal end of removal element 252 is proximal of the occlusionmaterial; (11) rotating the actuation control knob 374 to increase theexpansion of removal element 252, and proceeding to advance the removalelement 252 through the occlusion material again. This process iscontinued until a predetermined amount of the occlusion material isremoved. This description for using the present invention is onlyexemplary. Additional methods for using the present invention arecontained herein.

FIG. 19 is a partial sectioned side elevation view of another embodimentof an expandable vascular occlusion material removal device 250. Thedetailed construction of the drive assembly 283 and the removal element252 are more clearly shown in FIG. 20 and will be discussed in detaillater. However, a general description of the major subcomponents ofdrive assembly 283 will be presented with respect to the embodimentshown in FIG. 19.

Drive assembly 283 may comprise motor 274 for rotating inner drive shaft312 and outer drive shaft 314. As discussed in the text associated withFIG. 18, inner drive shaft 312 and outer drive shaft 314 are operativelycoupled to the removal element 252. Therefore, motor 274 may provide therotational force applied to removal element 252 for removing occlusionmaterial.

Drive assembly 283 may also comprise a power source 276, illustrated asa plurality of batteries electrically connected in series, forenergizing motor 274, and a control switch 278 connected electricallybetween the motor 274 and the power source 276 such that actuation ofthe control switch 278 allows current to flow between the power source276 and the motor 274, thereby causing motor 274 to rotate. The motor274 is attached to a set of gears 272 which transfers the torqueprovided by motor 274 to outer spline 268. Gears 272 may be in aone-to-one gear ratio but other gear ratios may be used to increase thepower or speed of the device. Gears 272 are preferably spur gears modelnumber 31800 available from Seitz Acetal Inc. but it is recognized thata suitable substitute may be available. In the exemplary embodiment ofthe invention, the motor 274 is a direct current micro-motor availablefrom Micro Mo Electronics, Inc. of St. Petersburg, Fla., model number2233T-04.5S, and the power source 276 comprises six (6) 1.5 Volt AAAlkaline batteries available from Duracell Corporation. It is recognizedthat there may be suitable substitutes for the above referenced elementsand that the suitable substitutes may achieve similar results.

The motor 274 can rotate an outer spline 268, and therefore inner driveshaft 312 and outer drive shaft 314, at a speed of about 10,000revolutions per minute, but it is envisioned that greater speeds, on theorder of 100,000 revolutions per minute may be possible with differentmotor 274. For example, motor 274 may be similar to the brushless directcurrent motor available from Transicoil Inc. of Valley Forge, Pa., modelnumber U-222285, which can reach speeds of 100,000 revolutions perminute. Thus, the removal device 250 could operate at speedssubstantially within the range of 0 to 100,000 revolutions per minute.It is contemplated that outer spline 268 could be coupled directly tothe drive shaft of motor 274 in a through-shaft configuration to achievesimilar results.

The torque from motor 274 is transferred to outer spline 268 via gears272. Outer spline 268 may be made from 3/32 square tubing that is 4.25inches long made from stainless steel, injection molded plastic,injection molded ultra high density molecular weight polyetholene(UHMN-PE), or the like. An inner spline 266 is telescopically connectedto outer spline 268. That is, the proximal end of inner spline 266 isreceived by the central cavity of the distal end of outer spline 268.Inner spline 266 is also made from square tubing so that when innerspline 266 is received by outer spline 268, torque is transferred fromouter spline 268 to inner spline 266. Inner spline 266 can slide in andout of outer spline 268 even while torque is applied by motor 274. It iscontemplated that spline 268 could be telescopically received by thecentral cavity of spline 266 and achieve the objectives of the presentinvention. It is also contemplated that inner spline 266 and outerspline 268 may have any cross sectional shape which allows a telescopicconnection and the transfer of torque.

Inner spline 266 is operatively coupled to a proximal end of actuationmechanism 264. Actuation mechanism 264 provides for the following twoprimary functions; (1) controlling gross longitudinal conjoint movementof inner drive shaft 312 and outer drive shaft 314 thereby causing theexpandable removal element 252 to move longitudinally therewith; and (2)controlling the relative shift between inner drive shaft 312 and anouter drive shaft 314 thereby causing the expandable removal element 252to move between a contracted position and an expanded position to engageocclusion material within the vascular lumen. Because of the telescopicinterface between inner spline 266 and outer spline 268, actuationmechanism 264 can move proximally or distally within drive assembly 283to provide conjoint movement of an inner drive shaft 312 and outer driveshaft 314. The details of actuation mechanism 264 will be discussedfurther in conjunction with FIGS. 20-21.

Two coaxial hypotubes extend from the distal end of actuation mechanism264 including an inner hypotube 318 (see FIG. 20) and an outer hypotube262. Inner hypotube 318 and outer hypotube 262 are preferably made fromstainless tubing coated with PTFE, injection molded plastic, injectionmolded ultra high density molecular weight polyetholene (UHMN-PE), orthe like. However, it is recognized that other materials will work aswell. The distal end of inner hypotube 318 is coupled to the proximalend of an inner drive shaft 312. The distal end of outer hypotube 262 iscoupled to the proximal end of an outer drive shaft 314. A detaileddescription of the inner drive shaft 312 and the outer drive shaft 314is contained in the text related to FIGS. 25-26. The inner drive shaft312 and outer drive shaft 314 exit the distal end of drive assembly 283,pass through strain relief 258 and are received by outer sheath 256.Outer drive shaft 314 is coupled to the proximal end of expandableremoval element 252. Inner drive shaft 312 passes through expandableremoval element 252 and is coupled to the distal end of the expandableremoval element 252. In this configuration, when inner drive shaft 312and outer drive shaft 314 are moved longitudinally relative to oneanother by rotating actuation control knob 374 (see FIG. 18), theexpandable removal element 252 moves between a contracted position andan expanded position thereby allowing expandable removal element 252 toengage or disengage intravascular occlusion material.

To insure that actuation mechanism 264 is able to move proximally anddistally and therefore allowing the inner drive shaft 312 and outerdrive shaft 314 and removal element 252 to move proximally and distallytherewith, outer sheath 256 does not extend completely to the proximalend of expandable removal element 252. However, a sheath 286 may extendover the resulting exposed portion of the outer drive shaft 314 andsubstantially under outer sheath 256 for a distance substantially thesame as, but greater than, that which actuation mechanism 264 can moveproximally and distally within drive assembly 283. Sheath 286 is used toensure that a vascular lumen is not in direct contact with the outerdrive shaft 314. Sheath 286 may be made from, or coated with, PTFE orother lubricous material.

Drive housing 283 also contains a motor circuit cavity 280 and batterypower supply 276. The motor control circuitry contained in motor circuitcavity 280 may provide several functions including a torque limitingfunction. When the physician is performing the atherectomy procedure,the interaction of expandable removal element 252 with the intravascularocclusion material will necessarily require motor 274 to provide varioustorque levels. If the physician has expanded removal element 252 too faror the physician is attempting to remove the intravascular occlusionmaterial to fast, the torque provided by motor 274 will increasesubstantially. The torque limiting function of the electric motorcontrol circuitry limits the level of torque that motor 274 can provideto a predetermined level. In one exemplary embodiment, the torque limitmay be set to a level equivalent to approximately one half of the torquethat the inner drive shaft 312 and the outer drive shaft 314 cansustain. In another exemplary embodiment, the torque limit may be set tothe maximum level that can be sustained without causing damage to thepatient's vascular system. It is contemplated that any predeterminedlimit may be is implemented in the torque limiting function.

An additional feature of the electric motor control circuitry is thatprior to limiting the torque of motor 274, a warning signal, for examplea tone or a light, is provided indicating to the physician that themaximum torque level is being approached. This feature enables thephysician to back off before the electric motor control circuitry limitsthe torque provided by motor 274. Finally, the electric motor controlcircuitry may provide a torque meter comprising a plurality of LEDelements. As the required torque increases, the number of LED elementsthat are turned on by the electric motor control circuitry is similarlyincreased. This provides the physician with an analog view of the torquedeveloped during the atherectomy procedure.

The electric motor control circuitry may also provide for voltageregulation to insure that the torque and speed of motor 274 is notdependent on the battery resistance. In the exemplary embodiment,battery power supply 276 comprises six (6) 1.5 volt AA Duracell Alkalinebatteries or the like connected in a series configuration. This resultsin approximately nine volts being supplied to the electric motor controlcircuitry. The voltage regulation feature regulates the nine voltsprovided by the battery power supply 276 to approximately six voltswhich is then ultimately supplied to motor 274. The voltage regulatorfeature of the motor control circuitry ensures that motor 274 operatesat the same speed and provides the same torque despite having a slightlydischarged battery power supply 276. In another embodiment, the voltageregulation level may be manually changed by the operator to increase thespeed or power of the removal device 250.

The present invention may be advanced over a guidewire 288. Theguidewire 288 may be received by removal element 252, inner drive shaft312, inner hypotube 318, actuation mechanism 264, inner spline 266,outer spline 268, and guidewire lock 270. Thus, removal device 250 is ofan over-the-wire construction which can facilitate removing the removaldevice 250 from, and replacing the removal device 250 in the patientbecause guidewire 288 can remain within the patient. Guidewire 288 mayalso provide support for removal element 252 within the vascular lumenof a patient. In an exemplary embodiment, guidewire 288 may be madeslightly stiffer than removal element 252 such that guidewire 288 mayhelp control the shape and position of removal element 252 within thevascular lumen, especially around corners. In addition, guidewire 288can be slid distally of removal element 252 for facilitatingintravascular navigation of removal element 252.

In an exemplary embodiment of the intravascular removal device 250, theguidewire 288 has an outer diameter measuring substantially within therange of 0.010" to 0.014". In addition, guidewire 288 is manufactured tobe slightly stiffer than the expandable removal element 252 and driveshaft assembly 257 to ensure that guidewire 288 has the ability tocontrol and direct the position of the expandable removal elementassembly within the vascular lumen. Also, the guidewire 288 may becoated with a low friction coating, such as a nickel-silver alloy likenikasil, or a fluoropolymer infused nickel substance like nedox, or anickel plating with PTFE spheres, for reducing friction between theguidewire 288 and the inner drive shaft 312. Finally, it is contemplatedthat guidewire 288 may have a 1 cm to 3 cm coiled tip at the distal endto be more easily navigated through the vascular structure. The distaltip of guidewire 288 may be made large enough such that removal element252 cannot be pushed distally thereof to prevent removal element 252from disengaging guidewire 288.

Guidewire lock 270 enables the physician to lock the guidewire inposition relative to drive assemble 283. The details of Guidewire lock270 are discussed fully above in the text relating to FIG. 2.

Finally, drive assembly 283 may comprise solution flush line 284. In oneembodiment of the present invention, solution flush line 284 supplies asaline solution under slight positive pressure to drive shaft assembly257. To insure the saline solution is in fluid communication with thecavity between inner drive shaft 312 and outer drive shaft 314 and thecavity within the inner drive shaft 312, holes 500 and 502 are providedfor in the distal end of outer hypotube 262 and inner hypotube 318,respectively. In this exemplary embodiment, the saline solution acts asa lubricant between the inner drive shaft 312 and the outer drive shaft314 as well as between the outer drive shaft 314 and outer sheath 256and finally between the inner drive shaft 312 and the guidewire 288. Thesaline solution also purges air from the drive shafts and providesirrigation to the removal element 252 to block blood and the like fromentering drive shaft assembly 257. Finally, solution flush line 284 canbe utilized for infusion of fluids, such as contrast media, a salinesolution, a drug therapy, and the like, into the patient, and foraspiration of the intravascular treatment site. Distal seal 260 providesa seal around outer hypotube 262 such that the saline solution providedby solution flush line 284 cannot flow proximally through the cavitydefined by outer hypotube 262 and an outer wall 317 (see FIG. 20).

FIG. 20 is an enlarged sectional view of FIG. 19 showing the details ofthe drive assembly 283 of an exemplary embodiment of the presentinvention. The torque from motor 274 is provided to outer spline 268 viagears 272 (gears 272 and motor 274 are shown in FIG. 19). Outer spline268 is telescopically coupled to inner spline 266 such that inner spline266 can slide proximally and distally with respect to outer spline 268.Outer spline 268 and inner spline 266 are shaped such that torque can beapplied from one to the other. An inner shaft bearing 302, preferablymodel number 7Y55-PSS 2507 available from Stock Drive Products, ispressed onto inner spline 266 such that if inner shaft bearing 302 ismoved proximally or distally, inner spline 266 moved conjointlytherewith. Inner shaft bearing 302 is coupled to an inner-actuatorhousing 306.

A rack gear 308, preferably made from nylon and available from StockDrive Products as model number A-1M12-N48, is coupled to inner-actuatorhousing 306. A pinion gear 310, preferably made from nylon and availablefrom Stock Drive Products as model number A-1M-2-N48012, engages rackgear 308 such that when pinion gear 310 is rotated, rack gear 308 movesrelative to pinion gear 310 either proximally or distally depending onthe direction of rotation. The movement of rack gear 308 is transmittedto inner spline 266 which moves conjointly with rack gear 308. Innerspline 266 is telescopically connected to outer actuation spline 298.Again, inner spline 266 and outer actuation spline 298 are shaped suchthat torque can be transmitted from one to the other. Therefore, innerspline 266 may slide proximally or distally with respect to outeractuation spline 298 in a telescoping fashion when pinion gear 310 isrotated. Inner spline 266 is operatively connected to the proximal endof inner hypotube 318. The distal end of inner hypotube 318 is coupledto inner drive shaft 312. Therefore, torque applied to inner spline 266by motor 274 can be transmitted to inner drive shaft 312.

As previously stated, inner spline 266 and outer actuation spline 298are shaped such that torque can be transferred from one to the other.Therefore, outer actuation spline 298 may rotate conjointly with innerspline 266. Outer actuation spline 298 is operatively coupled toreciprocating seal housing 294. Reciprocating seal housing 294 comprisesreciprocating seal 296 for preventing saline solution from traversingproximally of reciprocating seal housing 294 through the cavity definedby outer hypotube 262 and inner hypotube 318. Reciprocating seal housing294 is operatively connected to the proximal end of outer hypotube 262.The distal end of outer hypotube 262 is operatively connected to outerdrive shaft 314. Therefore, torque applied to inner spline 266 by motor274 can be transmitted to outer drive shaft 314. An outer shaft bearing300, preferably part number 7Y55-PSS 2512 available from Stock DriveProducts, is pressed onto outer hypotube 262 and further coupled toouter actuator housing 304. Outer shaft bearing 300 holds outer hypotube262 in a stationary position with respect to actuation mechanism 264.Quad ring seal 316 is provided around outer hypotube 262 to preventfluid from traversing proximally along the outer edge of outer hypotube262.

Guidewire 288, inner drive shaft 312 and outer drive shaft 314 traversecoaxially through outer sheath 256 to expandable removal element 252.Outer drive shaft 314 is operatively coupled to the proximal tip 336 ofexpandable removal element 252 and provides torque thereto. Inner driveshaft 312 traverses through expandable removal element 252 and isoperatively coupled to the distal tip 322 of expandable removal element252 and provides torque thereto. In one embodiment of the presentinvention, outer sheath 256 does not extend all the way to the proximaltip 336 of expandable removal element 252 thus exposing a portion ofouter drive shaft 314 to the vascular lumen of the patient. Outer driveshaft 314 may be shielded from direct contact with the vascular lumen bya coating 286 placed over outer drive shaft 314 that extends proximallyof the distal end of outer sheath 256 for a distance substantiallysimilar to, but greater than, the distance actuation mechanism can moveproximally and distally. The coating may be made from PTFE or the like.

As stated earlier, solution flush line 284 can be utilized for infusionof fluids, such as contrast media, a saline solution, a drug therapy,and the like, into the patient, and for aspiration of the intravasculartreatment site. This infused fluid can also provide for increasedlubrication to the drive shaft assembly 257, which may be beneficialduring operation of the motor 274, and for allowing irrigation of anintravascular treatment site, which may be necessary to maintain a fluidbalance within a vascular lumen if aspiration techniques are also used.Therefore, in one embodiment of the present invention, it is desirableto have saline solution flow into the inner cavity of inner drive shaft312, between inner drive shaft 312 and outer drive shaft 314, andbetween outer drive shaft 314 and outer sheath 256.

To enable fluid to enter the outer drive shaft 314 and inner drive shaft312, holes 500 are provided in the distal portion of outer hypotube 262and holes 502 are provided in the distal portion of inner hypotube 318.Therefore, solution flush line 284 is in fluid communication with theinner cavity of inner drive shaft 312, the cavity between inner driveshaft 312 and outer drive shaft 314, and the cavity between outer driveshaft 314 and outer sheath 256. The preferred pressure of the salinesolution results in approximately 10 cc of fluid being pumped intosolution flush line 284 per minute. However, all of the fluid suppliedto solution flush line 284 may not be delivered to removal element 252because some of the fluid may escape past quad ring seal 316,reciprocating seal 296, and the inner portion of inner spline 266.

An advantage of providing positive pressure to the saline solution isthat blood and other particulates are kept from entering the distal endof drive shaft assembly 257 and hence from causing friction therein.

It is undesirable to have saline solution or the like, provided bysolution flush line 284, to travel proximally of reciprocating sealhousing 294 and engage motor 274. Therefore, quad ring seal 316 preventsfluid from traveling proximally along the outer surface of outerhypotube 262. Reciprocating seal 296 prevents fluid from travelingproximally between inner hypotube 318 and outer hypotube 262. Finally,the inner portion of inner spline 266 is necked down to be in closetolerance with guidewire 288. The tolerance between guidewire 288 andthe inner portion of inner spline 266 is such that a significant amountof fluid cannot pass proximally of that point. The combination of thesethree seals prevents most fluid provided by solution flush line 284 fromflowing proximally to engage motor 274. A drain hole is supplied indrive housing 283 to allow any fluid that leaks past quad ring seal 316,reciprocating seal 296, and the inner portion of inner spline 266 todrain from drive housing 283 before reaching motor 274.

In some embodiments of the present invention, aspiration may be providedor enhanced by an impeller-like element operatively attached to thedrive shafts such that rotation of the drive shafts and the impellerelement generates a fluid flow within the vascular lumen, therebycausing particulates to flow into the space defined by outer sheath 256.In other embodiments, multiple impeller-like elements may be attached tothe drive shafts at various locations along the longitudinal axisthereof.

FIG. 21 is a sectional view along lines 21 of FIG. 18. The details ofone view of actuation mechanism 264 have already been described indetail in FIG. 20. However, a further description of a sectional view iscontained herein. Slide lock 376 passes through drive housing 282 andengages actuation sliding member 392. Actuation sliding member 392 iscoupled to advance control housing 382 and outer shaft bearing 300. Anouter shaft bearing 300 is pressed onto outer hypotube 262 such thatouter hypotube 262 moves conjointly with outer shaft bearing 300. Aninner shaft bearing 302 is pressed onto inner spline 266 such that innerspline 266 moves conjointly with inner shaft bearing 302. Inner spline266 is telescopically coupled to outer actuation spline 298 such thatinner spline 266 can move proximally and distally with respect to outeractuation spline 298. Inner shaft bearing 302 is pressed into inneractuation housing 306. Rack gear 308 is operatively coupled to inneractuator housing 306.

In addition, a spring 380 is placed in advancement control housing 382such that spring 380 engages actuation control knob 374 forcing it in anupward direction. This, in turn, forces pinion gear 310 also in anupward direction. Advancement control housing 382 has a set of gearteeth 381 located near pinion gear 310 to engage pinion gear 310 whenspring 380 forces pinion gear 310 upwardly. This, in effect, preventspinion gear 310 from rotating while spring 380 forces pinion gear 310 inan upward direction. To allow pinion gear 310 to rotate and cause innerspline 266 to move with respect to outer actuation spline 298, thephysician must depress actuation control knob 374 such that pinion gear310 does not engage teeth 381 provided on the advancement controlhousing 382 and only engages rack gear 308.

In the exemplary embodiment, outer actuation spline 298, reciprocatingseal housing 294, outer shaft bear 300, outer hypotube 262, and outerdrive shaft 314 are held stationary with respect to actuation slidingmember 392 and advancement control housing 382. Therefore, by depressingactuation control knob 374 and rotating it in either direction, piniongear 310 engages rack gear 308 and moves rack gear 308, inner actuatorhousing 306, inner shaft bearing 302, inner spline 266, and finallyinner drive shaft 312 with respect to outer drive shaft 314 therebycausing the removal element 252 to expand or contract depending on thedirection of rotation of actuation control knob 374. In the exemplaryembodiment, to slide removal element 252 to the expanded position, theactuation control knob is rotated clockwise thereby moving the innerdrive shaft 312 proximately with respect to the outer drive shaft 314.

The degree of expansion of removal element 252 is directly proportionalto the amount of relative sliding between the inner drive shaft 312 andthe outer drive shaft 314. Thus, the degree of expansion and/orcontraction of removal element 352 can be measured by suitable scalingmeans disposed on the drive housing 282 or on the actuation control knob374 as shown. When a desired degree of expansion of removal element 252has been achieved, the actuation control knob 374 can then be released.The spring 380 then expands and forces a portion of the teeth of piniongear 310 into engagement with teeth 381 located on the inner portion ofadvancement control housing 382, while a portion of the teeth on piniongear 310 remain engaged with the teeth located on rack gear 308.Interengagement of the teeth on pinion gear 310 with teeth 381 on theinner portion of advancement control housing 382 positively locks therelative axial position of inner drive shaft 312 and outer drive shaft314 and hence the expanded position of the material removal element 352.Therefore, the actuation mechanism 264 allows for a positivelycontrolled analog expansion of the removal element 252 by rotating theactuation control knob 274. It is contemplated that the presentembodiment of the present invention employs a radial expansion limitingmeans as described in FIG. 7 and FIG. 8.

An embodiment of the present invention allows actuation mechanism 264 tomove proximally and distally within elongated slot 390. This allows thephysician to move both inner drive shaft 312 and outer drive shaft 314conjointly in a proximal or distal direction. The degree of distal orproximal movement of the removal element 352 can be measured by suitablescaling means disposed on the drive housing 282 as shown. The physicianmay lock the position of the inner drive shaft 312 and outer drive shaft314 by turning slide lock 376 such that it engages actuation slidingmember 392 (see FIG. 21).

FIG. 22 is a sectional view of another embodiment of a vascularocclusion material removal device. This embodiment operates similar tothe embodiment described in FIG. 18, however, the actuation mechanism400 is somewhat different. In this embodiment, actuation mechanism 400is controlled by turning actuation control sleeve 420 rather thanactivation control knob 374 as in FIG. 21. Activation control sleeve 420engages outer activator spline 406 via screw-like threads. By turningactuation control sleeve 420, outer shaft bearing 404, outer activatorhousing 410, and outer activator spline 406 all move relative to inneractivator housing 408 and outer sheath 256. Therefore, in this exemplaryembodiment, the physician turns activation control sleeve 420 to moveouter drive shaft 314 distally with respect to inner drive shaft 312.

To longitudinally move inner drive shaft 312 and outer drive shaft 314conjointly, the physician places his hand on activation mechanism 400 ordirectly on the proximal end of outer sheath 422 and slides it in eithera proximal or distal direction. FIG. 22 shows activation mechanism 400moved to its furthest proximal position. As the physician movesactuation mechanism 400 distally, inner spline 412 telescopes out fromouter spline 414. As in the embodiment shown in FIG. 18, inner spline412 is telescopically coupled to outer spline 414. FIG. 22 shows innerspline 412 as being received by outer spline 414, however, it iscontemplated that inner spline 412 could receive outer spline 414 andachieve similar results. This embodiment also comprises a battery powersupply 428, a power switch 430, an electric DC motor 426, and gears 424.

FIG. 23 is an enlarged side elevational view of an exemplary embodimentof expandable removal element 252. Outer drive shaft 314 is operativelycoupled to proximal tip 336 of expandable removal element 252. Innerdrive shaft 312 extends through expandable removal element 252 and isoperatively coupled to distal tip 322. Guidewire 288 extends through thecenter of inner drive shaft 312 and extends distally of expandableremoval element 252. The cutting element of expandable removal element252 comprises a plurality of braided strands 324. Each strand within thebraid comprises at least one wire.

FIG. 24 shows a cross-section of one strand within the braid ofexpandable removal element 252 containing three wires per strand. Moreor less than three wires may be included in each strand. By increasingthe number of wires per strand, the surface area available for cuttingincreases. In addition, the "window" size between wires decreases, thusreducing the likelihood that large sections of the occlusion materialwill be broken away from the vascular lumen. Adding multiple wires perstrand, however, decreases the flexibility of the removal element.

One embodiment of the present invention uses a two over/two under braidpattern. Strand 324 passes over two strands at 334 and subsequentlypasses under two strands at 332. This is known as a two over/two underbraid pattern. Another embodiment of the present invention includes aone over/one under braid pattern (not shown). The braid pattern used ina particular embodiment of expandable removal element 252, along with anumber of wires per braid, define the cutting performance andflexibility of the expandable removal element 252.

The material removal element 252 of the exemplary embodiment generallycomprises a plurality, preferably about 8 to 48, of strands 324. Eachwire within strand 324 preferably has a substantially round latitudinalcross section having an outer diameter of about 0.001" to 0.005",although wires having flat, square, or triangular cross sections canalso be used. As stated in the previous paragraph, the wires 329 withineach braid comprise nitinol super-elastic wire, chromium-doped, having adiameter of about 0.002". In this embodiment, up to 48 strands arebraided at about 20 to 120 pics per inch and heat set at approximately350 degrees Celsius for about 30 minutes. In addition, the removalelement 252 has a length substantially within the range of about 0.5 cmto 3 cm, a contracted diameter substantially within the range of 1 mm to1.5 mm, and a maximum expanded diameter in the range of 2 mm to 4 mm.

The wires 329 within each strand may be made from any suitable material.However, it is recommended that the wires 329 be made from asuper-elastic or shape memory metal alloy, such as nitinol and the like,which allows the wires to recover from strains greater than thoserecoverable by other metals. This increased strain recovery allows thewires 329 to resist permanent deformation during repeated expansions andcontractions as well as during contact with vascular occlusion material.The use of super-elastic alloys for the wires within the braidsfacilitates return of the material removal element 252 to its originallow profile, contracted condition, which also makes intravascularnavigation of the material removal element 252 easier.

The outer surfaces of the wires 329 in the strands 324 may be sharpened,etched or coated with an abrasive 331, such as a diamond grit and thelike, to improve the removing or cutting characteristics of the removalelement 252. In one embodiment, a diamond grit having a grit sizesubstantially within the range of 3 to 100 microns is electroplated ontothe wires 329 in substantially uniform manner, however, the grit may beasymmetrically deposited on the wires 329 if desired. In anotherexemplary embodiment, the abrasive 331 may comprise a diamond grit orsynthetic abrasive, such as a cubic boron nitride and the like, having agrit size approximately within the range of 3 to 25 microns, attached tothe wires 329 by a nickel electroplating process.

Before the abrasive coating 331 is applied via a conventional nickelelectroplating process, a cleaning and pre-plating process may be usedto prepare wires 329. This process involves three basic steps: (1)performing an anodic caustic cleaning to degrease wires 329 and todecrease hydrogen embrittlement of the wire material during the nickelelectroplating process; (2) performing an anodic etch in sulfuric acidto remove oxide from the wire material and to decrease hydrogenembrittlement of the wire material during the nickel electroplatingprocess; and (3) performing a low phosphorous electroless nickel bathwherein in the reverse current or anodic mode of this step, oxide may beremoved from the wire material and in the direct current or cathodicmode of this step, a nickel plating substrate may be applied to wires329. After these cleaning and pre-plating steps are completed, wires 329may be plated with an abrasive coating as is conventional in the art. Itmay be desirable to shot peen wires 329 prior to the cleaning orpre-plating steps described herein above to clean wires 329 and toincrease the fatigue strength of wires 329 by compressing their surface.

It is contemplated that at least one of the plurality of wires containedin each braid of expandable removal element 252 can be replaced with awire made from a radiopaque material such as gold, platinum, or thelike. This allows the physician to observe the location of expandableremoval element 252 its expansion setting using X-ray or other means.

A distal tip 322 is attached to the distal end of the inner drive shaft312 by suitable means, such as an adhesive, solder, braze, weld, tinsolder mold, or mechanical swag, and the distal ends of the strands 324are attached to the distal tip 322 by similar means. Similarly, aproximal tip 336 is attached to the distal end of the outer drive shaft314 by suitable means, such as an adhesive, solder, braze, weld, or tinsolder mold, and the proximal ends of the strands 324 are attached tothe proximal tip 336 by similar means. Thus, the braided wires 329comprising the material removal element 252 rotate conjointly with driveshafts 312 and 314 and are under the influence of forces generated bythe motor 274. The distal tip 322 is provided with a cutting surfacelocated distally of the point of attachment of the wires 329. Thecutting surface may be coated with an abrasive, such as the diamond gritor synthetic abrasive as disclosed earlier.

FIG. 25 is an enlarged side elevational view of an exemplary embodimentof removal element 252. Outer drive shaft 314 is operatively coupled toa proximal tip 336 of removal element 252. Inner drive shaft 312 extendsthrough removal element 252 and is operatively coupled to a distal tip322. Guidewire 288 extends through the center of inner drive shaft 312and extends distally of removal element 252. The cutting means ofremoval element 252 comprises a plurality of braided strands 351.

FIG. 26 shows an expanded view of an exemplary embodiment of one strand351 within the braid pattern of removal element 252. The cutting meansof removal element 252 comprise a plurality of braided strands 351wherein each strand 351 is radially wrapped with a wrapping wire 342.Although only one primary braid wire 340 is shown per strand 351, it isrecognized that a number of primary braid wires 340 may be included ineach strand 351 of the braid. Also, primary braid wire 340 may bewrapped with a number of wrapping wires 342 before primary braid wires340 are braided together to form removal element 252. One advantage ofthe exemplary embodiment is that primary braid wire 340 may bemanufactured from a material with advantageous properties to enhanceproper expansion and contraction of removal element 252 while wrappingwire 342 may be made from a material which readily accepts an abrasivecoating 344. In addition, primary braid wire 340 may continually beexpanded and contracted as removal element 252 is expanded andcontracted and therefore primary braid wire 340 may experiencesignificant surface strain. Wrapping wire 342, on the other hand, is ina coil configuration wrapped around primary braid wire 340 and thereforemay not experience the same level of surface strain as primary braidwire 340. Therefore, abrasive coating 344 placed on wrapping wire 342may then last longer than if applied directly to the braid wire 340.

Primary braid wires 340 may be made from any suitable material. However,it is recommended that primary braid wires 340 be made from asuper-elastic or shape memory metal alloy, such as nitinol and the like,which allows the wires to recover from strains greater than thoserecoverable by other metals. This increased strain recovery allowsprimary braid wires 340 to resist permanent deformation during repeatedexpansions and contractions as well as during contact with vascularocclusion material. The use of super-elastic alloys for primary braidwires 340 within strands 351 facilitates return of removal element 252to its original low profile, contracted condition, which also easesintravascular navigation of removal element 252. It is also recommendedthat wrapping wires 342 be made from stainless steel or some othermaterial such as a radiopaque material that may be readily plated withabrasive 344.

Removal element 252 of this exemplary embodiment generally comprises aplurality, preferably about 8 to 48, of strands 351. Primary braid wires340 within each strand 351 preferably have a substantially roundlatitudinal cross section defining an outer diameter of about 0.001" to0.005", although wires having flat, square, or triangular cross sectionscan also be used. It is preferred that primary braid wires 340 withineach braid comprise nitinol super-elastic wire, chromium-doped, having adiameter of about 0.003". Wrapping wires 342 preferably have asubstantially round latitudinal cross section defining an outer diameterof about 0.001" to 0.005", although wires having flat, square, ortriangular cross sections can also be used. Wrapping wires 342preferably comprise stainless steel wire and are wound radially aroundprimary braid wires 340 with a spacing between adjacent coils of 0.002"to 0.005" with 0.0025" preferred. In this embodiment, up to 48 strands351 are braided together at about 20 to 120 pics per inch and heat setat approximately 350 degrees Celsius for about 30 minutes. The resultingbraid preferably has an overall length substantially within the range ofabout 0.5 cm to 3 cm, a contracted diameter substantially within therange of 1 mm to 1.5 mm, and a maximum expanded diameter in the range of2 mm to 4 mm. However, it is recognized that wrapping wire 342 maycomprise Elgiloy alloy which is a cobalt, chromium, nickel alloyavailable from Elgiloy Limited Partnership. It is further recognizedthat wrapping wire 342 may comprise Kevlar thread or any other suitablematerial.

One exemplary embodiment of the present invention uses a two over/twounder braid pattern. Another embodiment of the present invention uses aone over/one under braid pattern. The braid pattern used in a particularembodiment of removal element 252, along with the number of primarybraid wires 340 per strand 351, define the cutting characteristics andflexibility of removal element 252. It is recognized that differentbraid patterns and different numbers of primary braid wires 340 perstrand 351 may be used to obtain substantially similar results. Finally,it is recognized that each strand 351 within the braid pattern may beradially wrapped with a plurality of wrapping wires 342.

The outer surfaces of wrapping wires 342 may be sharpened, etched orcoated with abrasive 344, such as a diamond grit and the like, toimprove the removing or cutting characteristics of removal element 252.In one embodiment, a diamond grit having a grit size substantiallywithin the range of 3 to 100 microns is electroplated onto wrappingwires 342 in a substantially uniform manner, however, the grit may beasymmetrically deposited on wrapping wires 342 if desired. Naturaldiamonds are preferred over hand made diamonds because natural diamondshave a more jagged surface and therefore may be bonded to more easily.Natural diamonds also provide for better abrasive characteristics. Inanother exemplary embodiment, abrasive 344 may comprise a syntheticabrasive, such as a cubic boron nitride and the like, having a grit sizeapproximately within the range of 3 to 25 microns, attached to wrappingwires 342 by a nickel electroplating process known in the art.

To increase the flexibility of removal element 252, smaller abrasiveparticles and a thinner plating process may be used in plating removalelement 252. Also, because primary braid wires 340 experiences higherlevels of stress than wrapping wires 342, it is preferable to only platewrapping wires 342 with abrasive 344 and not plate the primary braidwire 340. This can be accomplished using known plating techniques.

Finally, bridging of abrasive plating 344 between coils 346 and 348 ofwrapping wire 342 is undesirable because cracking of the abrasiveplating can occur in these areas. Therefore, wrapping wire 342 may bewrapped such that coils 346 and 348 are a sufficient distance apart toprevent bridging between them during the plating process. The preferredspacing between adjacent coils of wrapping wire 342 may be 0.001" to0.005" with 0.0025" preferred.

Distal tip 322 is attached to the distal end of inner drive shaft 312 bysuitable means, such as an adhesive, solder, braze, weld, tin soldermold, or mechanical swag, and the distal ends of primary braid wires 340are attached to distal tip 322 by similar means. Similarly, proximal tip336 is attached to the distal end of outer drive shaft 314 by suitablemeans, such as an adhesive, solder, braze, weld, or tin solder mold, andthe proximal ends of primary braid wires 340 are attached to proximaltip 336 by similar means. Thus, primary braid wires 340 comprisingremoval element 252 rotate conjointly with drive shafts 312 and 314 andare under the influence of forces generated by motor 274. Distal tip 322is provided with a cutting surface located distally of the point ofattachment of primary braid wires 340. The cutting surface may be coatedwith an abrasive 319, such as the diamond grit or synthetic abrasivedisclosed earlier.

Finally, it is recognized that at least one of the plurality of primarybraid wires 340 and/or wrapping wires 342 may be replaced with a wiremade from a radiopaque material such that a physician can view theposition and the degree of expansion of removal element 252 using X-raysor similar means.

FIG. 27 is an enlarged partially-sectioned side elevational view of thedual drive shaft embodiment of the present invention. In the exemplaryembodiment, both inner drive shaft 312 and outer drive shaft 314comprise two oppositely wound helices. Inner drive shaft 312 comprisesan inner helix 362 and an outer helix 360. The inner helix 362 of innerdrive shaft 312 is formed by wires wound in a direction relative to theintended direction of rotation such that inner helix 362 may radiallyexpand upon rotation of the inner drive shaft 312. Outer helix 360,formed by wires wound in the opposite direction of inner helix 362 andsurrounds inner helix 362. Therefore, outer helix 360 is wound in adirection relative to the intended direction of rotation such that outerhelix 360 may radially contract upon rotation of inner drive shaft 312.The radial expansion of the inner helix 362 is balanced by the radiallycontraction of outer helix 360. Inner helix 362 and outer helix 360 maycontain the same number of windings per inch. Outer drive shaft 314 maybe formed in a similar manner.

Each helix is wound at a given winding angle whereby the winding angleis the angle of the coils of the helix to the latitudinal axis of thehelix. The winding angle of inner helix 362 and outer helix 360 dependsprimarily on the diameter of the wire used in the helix and on the majordiameter of the respective helix. To increase the winding angle of aparticular helix, a multi-filar coil configuration may be used. Amulti-filar configuration is a coil having a plurality of substantiallyparallel wires simultaneously wound to form a helix thereby increasingthe effective diameter of the wrapping wire while still maintaining alow profile helix. In the exemplary embodiment shown in FIG. 23, innerdrive shaft 312 and outer drive shaft 314 each have three (3) wireswound simultaneously, i.e. a three filar configuration, to increase thewinding angle of the coil. It is recognized that other numbers of wiresmay be used in the multi-filar configuration to achieve various windingangles.

Another advantage to having an increased winding angle in the helices isthat the flexibility of the helix may increased and that it may be lesslikely that the coils will overlap each other when the helix is bent.This is particularly important in the present application because thehelices are used in rotating drive shafts which must traverse acontorted vascular lumen. In addition, the increased winding angle mayreduce the interference between inner drive shaft 312 and outer driveshaft 314 when inner drive shaft 312 and outer drive shaft 314 are slidlongitudinally relative to one another.

The helices used in the inner drive shaft 312 and outer drive shaft 314may be prestressed by providing an axial torque about the longitudinalaxis of the wire used to form the helices while the wire is beingwrapped around a winding mandrel. In an exemplary embodiment, the axialtorque applied to the wire forming a helix may not exceed the linearelastic yield point of the wire. By prestressing the wires used to formthe helices in this manner, the initial expansion of the helices may bereduced when a longitudinal force is applied thereto thereby giving thehelices increased longitudinal strength. This may increase theresponsiveness of inner drive shaft 312 and outer drive shaft 314 whenlongitudinal force is applied to them, like for example, when slidinginner drive shaft 312 and outer drive shaft 314 relative to one anotherto expand and contract removal element 252. It is also recognized thatthe wires used to form the inner helix 362 and outer helix 360 canprestressed using conventional shot pinging techniques.

Outer drive shaft 314 receives inner drive shaft 312 such that innerdrive shaft 312 is slidable longitudinally with respect to outer driveshaft 314. Similarly to inner drive shaft 312, outer drive shaft 314comprises two oppositely wound helices. Outer drive shaft 314 isconstructed in a similar manner as inner drive shaft 312. The windingangle of the windings of outer drive shaft 314 may be less than thatemployed in inner drive shaft 312.

Another embodiment of inner drive shaft 312 and outer drive shaft 314comprises only a single wound helix. In this embodiment, the inner andouter drive shafts may axially expand or contract responsive to radialcontraction or expansion, respectively, thereof during operation of theremoval device 352. However, to combat this problem, the dual driveshaft configuration is preferred and may be constructed, byappropriately winding the inner and outer coils, to render axialexpansion and/or contraction of inner drive shaft 312 controllable. Bothinner drive shaft 312 and outer drive shaft 314 are received by outersheath 256 such that outer drive shaft 314 can rotatably and slidablymove within outer sheath 256. Outer sheath 256 may comprise an innersheath layer 292 and an outer sheath layer 290. Inner sheath layer 292may be thinner than outer sheath layer 290 and may be made from alubricous material. Outer sheath layer 290 may be made from a lowdensity material to keep outer sheath 256 flexible and is relativelythick to reduce the likelihood of kinking. However, the thickness of thedistal end of sheath 256 may be tapered down to provide a smoothtransition to outer drive shaft 314 or PTFE coating 286. It isenvisioned that the outer surface of outer sheath 256 may be coated witha hydrophilic coating or silicon coating to provide a lubricous surfacefor sliding within the vascular lumen. It is contemplated that theentire assembly including the inner drive shaft 312, the outer driveshaft 314, and the outer sheath 256 may be used in conjunction with aguide catheter.

In another embodiment of the present invention, a lubricous or lowfriction coating 367, comprised of a fluoropolymer and the like, can beapplied to the inner and/or outer surfaces of the inner drive shaft 312and the inner and/or outer surfaces of outer drive shaft 314. Thiscoating may improve trackability of the vascular material removal device250, as well as to reduce friction between the drive shafts and betweenthe outer drive shaft 314 and the outer sheath 256, and between theinner drive shaft 312 and the guidewire 288. The lubricous coating maybe provided in the form of a sheath of a fluoropolymer which shrinksupon application. In this manner, the lubricous coating can reducefriction between the drive shafts, provide the drive shafts withincreased torsional rigidity, limit radial expansion of the driveshafts, and form a fluid-tight lumen through the drive shafts. Thecoating can also aid proper aspiration through sheath 256 by minimizingfriction between the drive shafts and occlusion material aspirated intosheath 256.

FIG. 28 is an expanded partial sectional side view of another embodimentof inner drive shaft 312. In this embodiment, a ribbon 368 is woundaround inner helix 362 with a higher winding angle than that of innerhelix 362. In one embodiment of the present invention, ribbon 368 has arectangular cross section but it is recognized that any shape wire maybe used. In the exemplary embodiment, ribbon 368 is wound in the samedirection as inner helix 362 with a winding angle substantially the sameor larger than the winding angle of inner helix 362. However, it isenvisioned that ribbon 386 may have a winding angle substantially lessthan the winding angle of inner helix 362 or that ribbon 386 may beplaced longitudinally between inner helix 362 and outer helix 360 thushaving an effective wrapping angle of substantially 90 degrees. Ribbon368 provides additional longitudinal strength to inner drive shaft 312.It is contemplated that ribbon 368 could be applied to outer drive shaft314 in the same manner and that ribbon 368 could be wound in theopposite direction of the inner helix in either drive shaftconfiguration. Finally, it is contemplated that ribbon 368 could bewound around the outer helix of either inner drive shaft 312 and/orouter drive shaft 314.

It is contemplated that the inner drive shaft 312 and outer drive shaft314 construction may comprise any number of coaxial helices to obtainsimilar drive characteristics. Furthermore, it is contemplated that anynumber of coaxial drive shafts can be employed in the expandablevascular material removal device 250.

The various embodiments of the present invention also provide a numberof methods for performing intravascular treatments, such as removing ordisplacing vascular occlusion material. These methods comprise aplurality of steps, most of which have been discussed in detail withrespect to embodiments 10, 142, 176 and 218, so the following discussionof the methods will simply supplement those detailed discussions,instead of restating them, where appropriate.

The present expandable intravascular occlusion material removal deviceis inserted into the patient's vascular system through a suitablepuncture or other access site, such as via the femoral artery, in wellknown fashion. At this point, the expandable removal element 252 is inthe radially contracted position. The removal device 252 can be insertedthrough a conventional guide catheter, well known to those havingordinary skill in the relevant art. The removal device 252 is moved overguidewire 288, which has been previously positioned in proximity to theintravascular treatment site, until the distal end of the distal tip 322is adjacent the proximal end of the occlusion material to be removedthereby.

At any time, a fluid, such as saline, a drug therapy, heparinizedsaline, an oxygenated fluid, such as FLUORSOL, and the like, can beapplied to the solution flush line 284. The fluid flows along the axiallength of the drive shafts and passes into the hollow interior definedby the braided wires of removal element 252. At any time, another fluidto be infused into the patient, or a negative pressure to aspirate theintravascular treatment site may be applied to the solution flush line284 from a suitable source.

With the expandable material removal element 252 being positioned withrespect to the vascular occlusion material to be removed, the treatingphysician can expand the material removal element 252 to the desireddegree by turning the actuation control knob 374. The controlled, analogexpansion and contraction of the expandable removal element 252 canprovide a treating physician with the most flexibility in performingintravascular treatments, as well as possibly reducing the costs of suchtreatments because multiple pieces of equipment need not be used. Thisis a significant improvement over some of the intravascular treatmentdevices of the prior art. In addition, the various constructions of theremoval element radial expansion limiting means may insure that theremoval element 252 is not over-expanded (see FIG. 8 and FIG. 9). In oneexemplary embodiment of the radial expansion limiting means, the distalend of outer drive shaft 314 is extended a predetermined distance intothe braid portion of removal element 252 such that the distal tip 322 ofremoval element 252 may engage the distal end of outer drive shaft 314at a predetermined degree of radial expansion.

The removal device is now ready to remove vascular occlusion materialfrom a vascular surface or from a vascular occlusion by rotation of theexpandable material removal element 252. The treating physician actuatesthe control switch 278, thereby energizing the motor 274. The motor 274induces rotation of the inner drive shaft 312 and the outer drive shaft314, which, in turn, causes the removal element to rotate. The rotationof the material removal element 252 enables the sharp edges or abrasiveparticles on the surfaces of the braided wires to cut, abrade, ablate,or otherwise remove vascular occlusion material from a vascular lumensurface or a vascular occlusion. The physician then loosens slide lock376 and begins to slide the advancement control housing 382 proximallythus causing both the inner drive shaft 312 and the outer drive shaft314, and therefore the removal element 252, to move conjointly in theproximal direction. As the removal element 252 is moved proximally, itengages more occlusion material. The physician continually monitors ananalog torque signal, for example a variable tone or LED lights on thedrive housing, which indicate to the physician the torque provided bythe motor at any given time. The removal element is advanced through theocclusion material at a given expanded position. Once clear of thedistal side of the occlusion material, the physician will then rotatethe actuation control knob 374 to increase the expansion of the removalelement 252, and proceed to advance the removal element through theocclusion material again. This process is continued until a substantialportion of the occlusion material is removed.

This description of the method for using the exemplary embodiment or thepresent invention is only supplemental to those methods alreadydisclosed. It is contemplate that the methods disclosed previously doapply to the present exemplary embodiment.

While preferred embodiments of the present invention are shown anddescribed, it is envisioned that those skilled in the art may devisevarious modifications of the embodiments of the present inventionwithout departing from the spirit and scope of the appended claims.

What is claim is:
 1. A vascular occlusion material removal device forremoving vascular occlusion material in a vascular lumen, comprising:aremoval element having a proximal end and a distal end, and having asurface and an abrasive coating disposed thereon; and a distal tiplocated at said distal end of said removal element, said distal tiphaving a surface being less abrasive than said surface of said removalelement having an abrasive coating, wherein said abrasive surface ofsaid removal element is comprised of a plurality of strands which arcbraided together wherein each one of said plurality of strands comprisesat least one wire.
 2. A vascular occlusion material removal deviceaccording to claim 1 wherein the removal element is expandable and movesbetween a contracted position and an expanded position to allow saidremoval element to engage said vascular occlusion material within saidvascular lumen.
 3. A vascular occlusion material removal deviceaccording to claim 2 wherein a diameter of said removal element at saidabrasive surface when said removal element is in said contractedposition is equal to or less than a diameter of said distal tip.
 4. Avascular occlusion material removal device according to claim 3 whereinsaid diameter of said removal element at said abrasive surface ismeasured at a location approximately equidistant between said proximalend and said distal end of said removal element.
 5. A vascular occlusionmaterial removal device according to claim 4 further comprising aproximal tip located at said proximal end of said removal element, saidproximal tip having a surface being less abrasive than said removalelement.
 6. A vascular occlusion material removal device according toclaim 5 wherein said diameter of said removal element at said abrasivesurface when said removal element is in said contracted position isequal to or less than a diameter of said proximal tip.
 7. A vascularocclusion material removal device according to claim 6 furthercomprising:an outer drive shaft operatively coupled to said proximal tipto provide torque thereto; and an inner drive shaft disposed throughsaid removal element and operatively coupled to said distal tip, saidinner drive shaft being shiftable within said removal element and saidouter drive shaft, said inner drive shaft being shifted with respect tosaid removal element to expand said removal element from said contractedposition to said expanded position.
 8. A vascular occlusion materialremoval device according to claim 2 wherein said surface of said distaltip is smooth.
 9. A vascular occlusion material removal device accordingto claim 1 wherein said at least one wire used in said plurality ofstrands is coated with an abrasive material.
 10. A vascular occlusionmaterial removal device according to claim 1 wherein said plurality ofstrands are each wrapped circumferentially with at least one wrappingwire.
 11. A vascular occlusion material removal device according toclaim 10 wherein an abrasive material is deposited on said at least onewrapping wire.
 12. A vascular occlusion material removal deviceaccording to claim 1 wherein said plurality of strands have a diameterwhich is equal to or less than a diameter of said distal tip when saidremoval element is in said contracted position.